From 6d9defbb3e219aeabd0d1ddc49b712b99694b21e Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Sun, 4 Oct 2020 20:07:02 -0700
Subject: [PATCH 01/19] Add UWP Target

---
 BUILD.gn                                      |   5 +-
 shell/platform/windows/BUILD.gn               | 165 ++++++++++++++----
 .../platform/windows/client_wrapper/BUILD.gn  |   6 +-
 .../client_wrapper/flutter_view_controller.cc |   2 +
 .../include/flutter/flutter_view_controller.h |   2 +
 .../windows/flutter_project_bundle.cc         |   2 +-
 shell/platform/windows/flutter_windows.cc     |  24 ++-
 .../windows/flutter_windows_engine.cc         |   8 +
 .../platform/windows/flutter_windows_engine.h |  12 +-
 .../platform/windows/flutter_windows_view.cc  |   2 +
 shell/platform/windows/flutter_windows_view.h |   6 +-
 .../platform/windows/public/flutter_windows.h |   2 +
 shell/platform/windows/system_utils_winuwp.cc |  35 ++++
 tools/gn                                      |   5 +
 14 files changed, 236 insertions(+), 40 deletions(-)
 create mode 100644 shell/platform/windows/system_utils_winuwp.cc

diff --git a/BUILD.gn b/BUILD.gn
index 82575d2ff3755..08402b37f8daf 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -144,11 +144,14 @@ group("flutter") {
         public_deps += [ "//flutter/shell/platform/darwin/macos:flutter_desktop_darwin_unittests" ]
       }
 
-      if (is_win) {
+      if (is_win && target_os != "winuwp") {
         public_deps += [
           "//flutter/shell/platform/windows:flutter_windows_unittests",
           "//flutter/shell/platform/windows/client_wrapper:client_wrapper_windows_unittests",
         ]
+      } else if (is_win) {
+        # TODO once the UWP implmentation lands, reference future flutter_windows_unittests_winrt
+        # runner implementation from here
       }
     }
   }
diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index 66b578cf0fa49..7b98267ba8676 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -21,6 +21,11 @@ config("relative_flutter_windows_headers") {
   include_dirs = [ "public" ]
 }
 
+# When OS target is WinUWP use FLUTTER_WINUWP as the preprocessor flag to conditionalize
+config("flutter_windows_winuwp_defs") {
+  defines = [ "FLUTTER_WINUWP 1" ]
+}
+
 # The headers are a separate source set since the client wrapper is allowed
 # to depend on the public headers, but none of the rest of the code.
 source_set("flutter_windows_headers") {
@@ -29,8 +34,15 @@ source_set("flutter_windows_headers") {
   public_deps =
       [ "//flutter/shell/platform/common/cpp:common_cpp_library_headers" ]
 
-  configs +=
-      [ "//flutter/shell/platform/common/cpp:desktop_library_implementation" ]
+  if (target_os == "winuwp") {
+    configs += [
+      "//flutter/shell/platform/common/cpp:desktop_library_implementation",
+      ":flutter_windows_winuwp_defs",
+    ]
+  } else {
+    configs +=
+        [ "//flutter/shell/platform/common/cpp:desktop_library_implementation" ]
+  }
 
   public_configs =
       [ "//flutter/shell/platform/common/cpp:relative_flutter_library_headers" ]
@@ -100,6 +112,59 @@ source_set("flutter_windows_source") {
   ]
 }
 
+source_set("flutter_winuwp_source") {
+  sources = [
+    "angle_surface_manager.cc",
+    "angle_surface_manager.h",
+    "cursor_handler.cc",
+    "cursor_handler.h",
+    "flutter_project_bundle.cc",
+    "flutter_project_bundle.h",
+    "flutter_windows.cc",
+    "flutter_windows_engine.cc",
+    "flutter_windows_engine.h",
+    "flutter_windows_view.cc",
+    "flutter_windows_view.h",
+    "key_event_handler.cc",
+    "key_event_handler.h",
+    "keyboard_hook_handler.h",
+    "string_conversion.cc",
+    "string_conversion.h",
+    "system_utils.h",
+    "system_utils_winuwp.cc",
+    "text_input_plugin.cc",
+    "text_input_plugin.h",
+    "window_binding_handler.h",
+    "window_binding_handler_delegate.h",
+    "window_state.h",
+  ]
+
+  configs += [
+    "//flutter/shell/platform/common/cpp:desktop_library_implementation",
+    "//third_party/angle:gl_prototypes",
+    ":flutter_windows_winuwp_defs",
+  ]
+
+  public_configs = [ ":relative_angle_headers" ]
+
+  deps = [
+    ":flutter_windows_headers",
+    "//flutter/shell/platform/common/cpp:common_cpp",
+    "//flutter/shell/platform/common/cpp:common_cpp_input",
+    "//flutter/shell/platform/common/cpp:common_cpp_switches",
+    "//flutter/shell/platform/common/cpp/client_wrapper:client_wrapper",
+    "//flutter/shell/platform/embedder:embedder_as_internal_library",
+    "//flutter/shell/platform/windows/client_wrapper:client_wrapper_windows",
+    "//third_party/angle:libEGL_static",  # the order of libEGL_static and
+                                          # libGLESv2_static is important.. if
+                                          # reversed, will cause a linker error
+                                          # DllMain already defined in
+                                          # LIBCMTD.lib
+    "//third_party/angle:libGLESv2_static",
+    "//third_party/rapidjson",
+  ]
+}
+
 copy("publish_headers_windows") {
   sources = _public_headers
   outputs = [ "$root_out_dir/{{source_file_part}}" ]
@@ -114,36 +179,67 @@ shared_library("flutter_windows") {
   public_configs = [ "//flutter:config" ]
 }
 
+shared_library("flutter_windows_winuwp") {
+  deps = [ ":flutter_winuwp_source" ]
+  libs = [ "windowsapp.lib" ]
+  public_configs = [ "//flutter:config" ]
+}
+
 test_fixtures("flutter_windows_fixtures") {
   fixtures = []
 }
 
-executable("flutter_windows_unittests") {
-  testonly = true
+if (target_os == "winuwp") {
+  # disabled until the uwp implementation is present
+  # executable("flutter_windows_unittests_winrt") {
+  #   testonly = true
 
-  sources = [
-    "flutter_project_bundle_unittests.cc",
-    "string_conversion_unittests.cc",
-    "system_utils_unittests.cc",
-    "testing/mock_win32_window.cc",
-    "testing/mock_win32_window.h",
-    "testing/win32_flutter_window_test.cc",
-    "testing/win32_flutter_window_test.h",
-    "win32_dpi_utils_unittests.cc",
-    "win32_flutter_window_unittests.cc",
-    "win32_window_proc_delegate_manager_unittests.cc",
-    "win32_window_unittests.cc",
-  ]
+  #   sources = [
+  #     "flutter_project_bundle_unittests.cc",
+  #     "string_conversion_unittests.cc",
+  #     "system_utils_unittests.cc",
+  #   ]
 
-  public_configs = [ "//flutter:config" ]
+  #   public_configs = [ "//flutter:config" ]
 
-  deps = [
-    ":flutter_windows_fixtures",
-    ":flutter_windows_headers",
-    ":flutter_windows_source",
-    "//flutter/testing",
-    "//third_party/rapidjson",
-  ]
+  #     libs = [ "windowsapp.lib" ]
+
+  #   deps = [
+  #     ":flutter_windows_fixtures",
+  #     ":flutter_windows_headers",
+  #     ":flutter_windows_source",
+  #     "//flutter/testing",
+  #     "//third_party/rapidjson",
+  #   ]
+  # }
+} else {
+  executable("flutter_windows_unittests") {
+    testonly = true
+
+    sources = [
+      "flutter_project_bundle_unittests.cc",
+      "string_conversion_unittests.cc",
+      "system_utils_unittests.cc",
+      "testing/mock_win32_window.cc",
+      "testing/mock_win32_window.h",
+      "testing/win32_flutter_window_test.cc",
+      "testing/win32_flutter_window_test.h",
+      "win32_dpi_utils_unittests.cc",
+      "win32_flutter_window_unittests.cc",
+      "win32_window_proc_delegate_manager_unittests.cc",
+      "win32_window_unittests.cc",
+    ]
+
+    public_configs = [ "//flutter:config" ]
+
+    deps = [
+      ":flutter_windows_fixtures",
+      ":flutter_windows_headers",
+      ":flutter_windows_source",
+      "//flutter/testing",
+      "//third_party/rapidjson",
+    ]
+  }
 }
 
 shared_library("flutter_windows_glfw") {
@@ -162,11 +258,20 @@ group("windows_glfw") {
 }
 
 group("windows") {
-  deps = [
-    ":flutter_windows",
-    ":publish_headers_windows",
-    "//flutter/shell/platform/windows/client_wrapper:publish_wrapper_windows",
-  ]
+  if (target_os == "winuwp") {
+    deps = [
+      ":flutter_windows_winuwp",
+      ":publish_headers_windows",
+      "//flutter/shell/platform/windows/client_wrapper:publish_wrapper_windows",
+    ]
+  } else {
+    deps = [
+      ":flutter_windows",
+      ":publish_headers_windows",
+      "//flutter/shell/platform/windows/client_wrapper:publish_wrapper_windows",
+    ]
+  }
+
   if (build_glfw_shell) {
     deps += [ ":windows_glfw" ]
   }
diff --git a/shell/platform/windows/client_wrapper/BUILD.gn b/shell/platform/windows/client_wrapper/BUILD.gn
index fe54c2ba2a484..155d87575e74f 100644
--- a/shell/platform/windows/client_wrapper/BUILD.gn
+++ b/shell/platform/windows/client_wrapper/BUILD.gn
@@ -39,8 +39,10 @@ source_set("client_wrapper_windows") {
     "//flutter/shell/platform/windows:flutter_windows_headers",
   ]
 
-  configs +=
-      [ "//flutter/shell/platform/common/cpp:desktop_library_implementation" ]
+  configs += [
+    "//flutter/shell/platform/common/cpp:desktop_library_implementation",
+    "//flutter/shell/platform/windows:flutter_windows_winuwp_defs",
+  ]
 
   public_configs = [
     ":relative_core_wrapper_headers",
diff --git a/shell/platform/windows/client_wrapper/flutter_view_controller.cc b/shell/platform/windows/client_wrapper/flutter_view_controller.cc
index 5cb9fe98623e1..65817524f8497 100644
--- a/shell/platform/windows/client_wrapper/flutter_view_controller.cc
+++ b/shell/platform/windows/client_wrapper/flutter_view_controller.cc
@@ -29,6 +29,7 @@ FlutterViewController::~FlutterViewController() {
   }
 }
 
+#ifndef FLUTTER_WINUWP
 std::optional<LRESULT> FlutterViewController::HandleTopLevelWindowProc(
     HWND hwnd,
     UINT message,
@@ -39,5 +40,6 @@ std::optional<LRESULT> FlutterViewController::HandleTopLevelWindowProc(
       controller_, hwnd, message, wparam, lparam, &result);
   return handled ? result : std::optional<LRESULT>(std::nullopt);
 }
+#endif
 
 }  // namespace flutter
diff --git a/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h b/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h
index 7231fb790b450..916ee4dfd35cf 100644
--- a/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h
+++ b/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h
@@ -46,6 +46,7 @@ class FlutterViewController {
   // Returns the view managed by this controller.
   FlutterView* view() { return view_.get(); }
 
+#ifndef FLUTTER_WINUWP
   // Allows the Flutter engine and any interested plugins an opportunity to
   // handle the given message.
   //
@@ -55,6 +56,7 @@ class FlutterViewController {
                                                   UINT message,
                                                   WPARAM wparam,
                                                   LPARAM lparam);
+  #endif
 
  private:
   // Handle for interacting with the C API's view controller, if any.
diff --git a/shell/platform/windows/flutter_project_bundle.cc b/shell/platform/windows/flutter_project_bundle.cc
index 4b2c8dfef69be..833c197875122 100644
--- a/shell/platform/windows/flutter_project_bundle.cc
+++ b/shell/platform/windows/flutter_project_bundle.cc
@@ -7,7 +7,7 @@
 #include <filesystem>
 #include <iostream>
 
-#include "flutter/shell/platform/common/cpp/engine_switches.h"
+#include "flutter/shell/platform/common/cpp/engine_switches.h"  // nogncheck
 #include "flutter/shell/platform/common/cpp/path_utils.h"
 
 namespace flutter {
diff --git a/shell/platform/windows/flutter_windows.cc b/shell/platform/windows/flutter_windows.cc
index d5963a2122632..29424bfa1c235 100644
--- a/shell/platform/windows/flutter_windows.cc
+++ b/shell/platform/windows/flutter_windows.cc
@@ -22,9 +22,11 @@
 #include "flutter/shell/platform/windows/flutter_project_bundle.h"
 #include "flutter/shell/platform/windows/flutter_windows_engine.h"
 #include "flutter/shell/platform/windows/flutter_windows_view.h"
-#include "flutter/shell/platform/windows/win32_dpi_utils.h"
-#include "flutter/shell/platform/windows/win32_flutter_window.h"
-#include "flutter/shell/platform/windows/win32_task_runner.h"
+#ifndef FLUTTER_WINUWP
+#include "flutter/shell/platform/windows/win32_dpi_utils.h"       // nogncheck
+#include "flutter/shell/platform/windows/win32_flutter_window.h"  // nogncheck
+#include "flutter/shell/platform/windows/win32_task_runner.h"     // nogncheck
+#endif
 #include "flutter/shell/platform/windows/window_binding_handler.h"
 #include "flutter/shell/platform/windows/window_state.h"
 
@@ -56,6 +58,7 @@ FlutterDesktopViewControllerRef FlutterDesktopViewControllerCreate(
     int width,
     int height,
     FlutterDesktopEngineRef engine) {
+#ifndef FLUTTER_WINUWP
   std::unique_ptr<flutter::WindowBindingHandler> window_wrapper =
       std::make_unique<flutter::Win32FlutterWindow>(width, height);
 
@@ -76,6 +79,9 @@ FlutterDesktopViewControllerRef FlutterDesktopViewControllerCreate(
   // Must happen after engine is running.
   state->view->SendInitialBounds();
   return state.release();
+#else
+  return nullptr;
+#endif
 }
 
 void FlutterDesktopViewControllerDestroy(
@@ -93,6 +99,7 @@ FlutterDesktopViewRef FlutterDesktopViewControllerGetView(
   return HandleForView(controller->view.get());
 }
 
+#ifndef FLUTTER_WINUWP
 bool FlutterDesktopViewControllerHandleTopLevelWindowProc(
     FlutterDesktopViewControllerRef controller,
     HWND hwnd,
@@ -109,6 +116,7 @@ bool FlutterDesktopViewControllerHandleTopLevelWindowProc(
   }
   return delegate_result.has_value();
 }
+#endif
 
 FlutterDesktopEngineRef FlutterDesktopEngineCreate(
     const FlutterDesktopEngineProperties& engine_properties) {
@@ -133,7 +141,11 @@ bool FlutterDesktopEngineRun(FlutterDesktopEngineRef engine,
 }
 
 uint64_t FlutterDesktopEngineProcessMessages(FlutterDesktopEngineRef engine) {
+#ifndef FLUTTER_WINUWP
   return EngineFromHandle(engine)->task_runner()->ProcessTasks().count();
+#else
+  return 0;
+#endif
 }
 
 void FlutterDesktopEngineReloadSystemFonts(FlutterDesktopEngineRef engine) {
@@ -168,17 +180,22 @@ void FlutterDesktopPluginRegistrarRegisterTopLevelWindowProcDelegate(
     FlutterDesktopPluginRegistrarRef registrar,
     FlutterDesktopWindowProcCallback delegate,
     void* user_data) {
+#ifndef FLUTTER_WINUWP
   registrar->engine->window_proc_delegate_manager()
       ->RegisterTopLevelWindowProcDelegate(delegate, user_data);
+#endif
 }
 
 void FlutterDesktopPluginRegistrarUnregisterTopLevelWindowProcDelegate(
     FlutterDesktopPluginRegistrarRef registrar,
     FlutterDesktopWindowProcCallback delegate) {
+#ifndef FLUTTER_WINUWP
   registrar->engine->window_proc_delegate_manager()
       ->UnregisterTopLevelWindowProcDelegate(delegate);
+#endif
 }
 
+#ifndef FLUTTER_WINUWP
 UINT FlutterDesktopGetDpiForHWND(HWND hwnd) {
   return flutter::GetDpiForHWND(hwnd);
 }
@@ -186,6 +203,7 @@ UINT FlutterDesktopGetDpiForHWND(HWND hwnd) {
 UINT FlutterDesktopGetDpiForMonitor(HMONITOR monitor) {
   return flutter::GetDpiForMonitor(monitor);
 }
+#endif
 
 void FlutterDesktopResyncOutputStreams() {
   FILE* unused;
diff --git a/shell/platform/windows/flutter_windows_engine.cc b/shell/platform/windows/flutter_windows_engine.cc
index d70ca504c1b56..ffd834a70c392 100644
--- a/shell/platform/windows/flutter_windows_engine.cc
+++ b/shell/platform/windows/flutter_windows_engine.cc
@@ -91,6 +91,7 @@ FlutterLocale CovertToFlutterLocale(const LanguageInfo& info) {
 
 FlutterWindowsEngine::FlutterWindowsEngine(const FlutterProjectBundle& project)
     : project_(std::make_unique<FlutterProjectBundle>(project)) {
+#ifndef FLUTTER_WINUWP
   task_runner_ = std::make_unique<Win32TaskRunner>(
       GetCurrentThreadId(), [this](const auto* task) {
         if (!engine_) {
@@ -102,6 +103,7 @@ FlutterWindowsEngine::FlutterWindowsEngine(const FlutterProjectBundle& project)
           std::cerr << "Failed to post an engine task." << std::endl;
         }
       });
+#endif
 
   // Set up the legacy structs backing the API handles.
   messenger_ = std::make_unique<FlutterDesktopMessenger>();
@@ -111,8 +113,10 @@ FlutterWindowsEngine::FlutterWindowsEngine(const FlutterProjectBundle& project)
 
   message_dispatcher_ =
       std::make_unique<IncomingMessageDispatcher>(messenger_.get());
+#ifndef FLUTTER_WINUWP
   window_proc_delegate_manager_ =
       std::make_unique<Win32WindowProcDelegateManager>();
+#endif
 }
 
 FlutterWindowsEngine::~FlutterWindowsEngine() {
@@ -143,6 +147,7 @@ bool FlutterWindowsEngine::RunWithEntrypoint(const char* entrypoint) {
       switches.begin(), switches.end(), std::back_inserter(argv),
       [](const std::string& arg) -> const char* { return arg.c_str(); });
 
+#ifndef FLUTTER_WINUWP
   // Configure task runners.
   FlutterTaskRunnerDescription platform_task_runner = {};
   platform_task_runner.struct_size = sizeof(FlutterTaskRunnerDescription);
@@ -159,6 +164,7 @@ bool FlutterWindowsEngine::RunWithEntrypoint(const char* entrypoint) {
   FlutterCustomTaskRunners custom_task_runners = {};
   custom_task_runners.struct_size = sizeof(FlutterCustomTaskRunners);
   custom_task_runners.platform_task_runner = &platform_task_runner;
+#endif
 
   FlutterProjectArgs args = {};
   args.struct_size = sizeof(FlutterProjectArgs);
@@ -172,7 +178,9 @@ bool FlutterWindowsEngine::RunWithEntrypoint(const char* entrypoint) {
     auto host = static_cast<FlutterWindowsEngine*>(user_data);
     return host->HandlePlatformMessage(engine_message);
   };
+#ifndef FLUTTER_WINUWP
   args.custom_task_runners = &custom_task_runners;
+#endif
   if (aot_data_) {
     args.aot_data = aot_data_.get();
   }
diff --git a/shell/platform/windows/flutter_windows_engine.h b/shell/platform/windows/flutter_windows_engine.h
index 49c0fc7f2a8cf..c8c803dcbe21b 100644
--- a/shell/platform/windows/flutter_windows_engine.h
+++ b/shell/platform/windows/flutter_windows_engine.h
@@ -13,8 +13,10 @@
 #include "flutter/shell/platform/common/cpp/incoming_message_dispatcher.h"
 #include "flutter/shell/platform/windows/flutter_project_bundle.h"
 #include "flutter/shell/platform/windows/public/flutter_windows.h"
-#include "flutter/shell/platform/windows/win32_task_runner.h"
-#include "flutter/shell/platform/windows/win32_window_proc_delegate_manager.h"
+#ifndef FLUTTER_WINUWP
+#include "flutter/shell/platform/windows/win32_task_runner.h"  // nogncheck
+#include "flutter/shell/platform/windows/win32_window_proc_delegate_manager.h"  // nogncheck
+#endif
 #include "flutter/shell/platform/windows/window_state.h"
 
 namespace flutter {
@@ -73,11 +75,13 @@ class FlutterWindowsEngine {
     return message_dispatcher_.get();
   }
 
+#ifndef FLUTTER_WINUWP
   Win32TaskRunner* task_runner() { return task_runner_.get(); }
 
   Win32WindowProcDelegateManager* window_proc_delegate_manager() {
     return window_proc_delegate_manager_.get();
   }
+#endif
 
   // Callback passed to Flutter engine for notifying window of platform
   // messages.
@@ -101,8 +105,10 @@ class FlutterWindowsEngine {
   // The view displaying the content running in this engine, if any.
   FlutterWindowsView* view_ = nullptr;
 
+#ifndef FLUTTER_WINUWP
   // Task runner for tasks posted from the engine.
   std::unique_ptr<Win32TaskRunner> task_runner_;
+#endif
 
   // The plugin messenger handle given to API clients.
   std::unique_ptr<FlutterDesktopMessenger> messenger_;
@@ -118,8 +124,10 @@ class FlutterWindowsEngine {
   FlutterDesktopOnPluginRegistrarDestroyed
       plugin_registrar_destruction_callback_;
 
+#ifndef FLUTTER_WINUWP
   // The manager for WindowProc delegate registration and callbacks.
   std::unique_ptr<Win32WindowProcDelegateManager> window_proc_delegate_manager_;
+#endif
 };
 
 }  // namespace flutter
diff --git a/shell/platform/windows/flutter_windows_view.cc b/shell/platform/windows/flutter_windows_view.cc
index 415f074a8e99f..db47d27ac6da1 100644
--- a/shell/platform/windows/flutter_windows_view.cc
+++ b/shell/platform/windows/flutter_windows_view.cc
@@ -39,8 +39,10 @@ void FlutterWindowsView::SetEngine(
       std::make_unique<flutter::KeyEventHandler>(internal_plugin_messenger));
   keyboard_hook_handlers_.push_back(
       std::make_unique<flutter::TextInputPlugin>(internal_plugin_messenger));
+#ifndef FLUTTER_WINUWP
   platform_handler_ = std::make_unique<flutter::PlatformHandler>(
       internal_plugin_messenger, this);
+#endif
   cursor_handler_ = std::make_unique<flutter::CursorHandler>(
       internal_plugin_messenger, binding_handler_.get());
 
diff --git a/shell/platform/windows/flutter_windows_view.h b/shell/platform/windows/flutter_windows_view.h
index f4e1186c6e034..c88b8ad2bbe53 100644
--- a/shell/platform/windows/flutter_windows_view.h
+++ b/shell/platform/windows/flutter_windows_view.h
@@ -20,7 +20,9 @@
 #include "flutter/shell/platform/windows/keyboard_hook_handler.h"
 #include "flutter/shell/platform/windows/public/flutter_windows.h"
 #include "flutter/shell/platform/windows/text_input_plugin.h"
-#include "flutter/shell/platform/windows/win32_platform_handler.h"
+#ifndef FLUTTER_WINUWP
+#include "flutter/shell/platform/windows/win32_platform_handler.h"  // nogncheck
+#endif
 #include "flutter/shell/platform/windows/window_binding_handler.h"
 #include "flutter/shell/platform/windows/window_binding_handler_delegate.h"
 #include "flutter/shell/platform/windows/window_state.h"
@@ -198,8 +200,10 @@ class FlutterWindowsView : public WindowBindingHandlerDelegate {
   std::vector<std::unique_ptr<flutter::KeyboardHookHandler>>
       keyboard_hook_handlers_;
 
+#ifndef FLUTTER_WINUWP
   // Handler for the flutter/platform channel.
   std::unique_ptr<flutter::PlatformHandler> platform_handler_;
+#endif
 
   // Handler for cursor events.
   std::unique_ptr<flutter::CursorHandler> cursor_handler_;
diff --git a/shell/platform/windows/public/flutter_windows.h b/shell/platform/windows/public/flutter_windows.h
index 25414937e54f6..27e018524834a 100644
--- a/shell/platform/windows/public/flutter_windows.h
+++ b/shell/platform/windows/public/flutter_windows.h
@@ -85,6 +85,7 @@ FLUTTER_EXPORT FlutterDesktopEngineRef FlutterDesktopViewControllerGetEngine(
 FLUTTER_EXPORT FlutterDesktopViewRef
 FlutterDesktopViewControllerGetView(FlutterDesktopViewControllerRef controller);
 
+  #ifndef FLUTTER_WINUWP
 // Allows the Flutter engine and any interested plugins an opportunity to
 // handle the given message.
 //
@@ -97,6 +98,7 @@ FLUTTER_EXPORT bool FlutterDesktopViewControllerHandleTopLevelWindowProc(
     WPARAM wparam,
     LPARAM lparam,
     LRESULT* result);
+#endif
 
 // ========== Engine ==========
 
diff --git a/shell/platform/windows/system_utils_winuwp.cc b/shell/platform/windows/system_utils_winuwp.cc
new file mode 100644
index 0000000000000..4d693def5a758
--- /dev/null
+++ b/shell/platform/windows/system_utils_winuwp.cc
@@ -0,0 +1,35 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/windows/system_utils.h"
+
+#include <Windows.h>
+
+#include <sstream>
+
+#include "flutter/shell/platform/windows/string_conversion.h"
+
+namespace flutter {
+
+std::vector<LanguageInfo> GetPreferredLanguageInfo() {
+  std::vector<std::wstring> languages = GetPreferredLanguages();
+  std::vector<LanguageInfo> language_info;
+  // TODO populate via WinRT
+  return language_info;
+}
+
+std::vector<std::wstring> GetPreferredLanguages() {
+  std::vector<std::wstring> languages;
+  // TODO populate via WinRT
+  return languages;
+}
+
+LanguageInfo ParseLanguageName(std::wstring language_name) {
+  LanguageInfo info;
+
+  // TODO populate via WinRT
+  return info;
+}
+
+}  // namespace flutter
diff --git a/tools/gn b/tools/gn
index 7514665b2dd6e..1ee74de6e5760 100755
--- a/tools/gn
+++ b/tools/gn
@@ -139,6 +139,10 @@ def to_gn_args(args):
     elif args.target_os == 'fuchsia':
         gn_args['target_os'] = 'fuchsia'
         gn_args['flutter_enable_legacy_fuchsia_embedder'] = args.fuchsia_legacy
+    elif args.target_os == 'winuwp':
+        gn_args['target_os'] = 'winuwp'
+        # Enabling angle_is_winuwp is dependent on an in-flight patch to https://chromium.googlesource.com/angle/angle to update UWP support
+        # gn_args['angle_is_winuwp'] = True
     elif args.target_os is not None:
         gn_args['target_os'] = args.target_os
 
@@ -316,6 +320,7 @@ def parse_args(args):
   parser.add_argument('--fuchsia', dest='target_os', action='store_const', const='fuchsia')
   parser.add_argument('--fuchsia-legacy', default=True, action='store_true')
   parser.add_argument('--no-fuchsia-legacy', dest='fuchsia_legacy', action='store_false')
+  parser.add_argument('--winuwp', dest='target_os', action='store_const', const='winuwp')
 
   parser.add_argument('--linux-cpu', type=str, choices=['x64', 'x86', 'arm64', 'arm'])
   parser.add_argument('--fuchsia-cpu', type=str, choices=['x64', 'arm64'], default = 'x64')

From df7af06f4c590fb7b47d9a0778bd11cf8e6eba41 Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Sat, 31 Oct 2020 08:48:21 -0700
Subject: [PATCH 02/19] CR feedback

---
 BUILD.gn                                      |  18 +--
 shell/platform/windows/BUILD.gn               | 118 +++++-------------
 .../client_wrapper/flutter_view_controller.cc |   2 +-
 .../include/flutter/flutter_view_controller.h |   2 +-
 shell/platform/windows/flutter_windows.cc     |  20 +--
 .../windows/flutter_windows_engine.cc         |   7 +-
 .../platform/windows/flutter_windows_engine.h |   8 +-
 .../platform/windows/flutter_windows_view.cc  |   2 +-
 shell/platform/windows/flutter_windows_view.h |   4 +-
 .../platform/windows/public/flutter_windows.h |   2 +-
 10 files changed, 64 insertions(+), 119 deletions(-)

diff --git a/BUILD.gn b/BUILD.gn
index 4d5a9a51cd47b..8eefbf9b7dcd1 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -145,14 +145,16 @@ group("flutter") {
         public_deps += [ "//flutter/shell/platform/darwin/macos:flutter_desktop_darwin_unittests" ]
       }
 
-      if (is_win && target_os != "winuwp") {
-        public_deps += [
-          "//flutter/shell/platform/windows:flutter_windows_unittests",
-          "//flutter/shell/platform/windows/client_wrapper:client_wrapper_windows_unittests",
-        ]
-      } else if (is_win) {
-        # TODO once the UWP implmentation lands, reference future flutter_windows_unittests_winrt
-        # runner implementation from here
+      if (is_win) {
+        if (target_os == "winuwp") {
+          # TODO once the UWP implmentation lands, reference future flutter_windows_unittests_winrt
+          # runner implementation from here.
+        } else {
+          public_deps += [
+            "//flutter/shell/platform/windows:flutter_windows_unittests",
+            "//flutter/shell/platform/windows/client_wrapper:client_wrapper_windows_unittests",
+          ]
+        }
       }
     }
   }
diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index 7b98267ba8676..1bf1ac0302947 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -21,9 +21,10 @@ config("relative_flutter_windows_headers") {
   include_dirs = [ "public" ]
 }
 
-# When OS target is WinUWP use FLUTTER_WINUWP as the preprocessor flag to conditionalize
+# TODO: Move to builtroot build/config/win/BUILD.gn when the UWP compliant change to that project lands.
+# When OS target is WinUWP use WINUWP as the preprocessor flag to conditionalize.
 config("flutter_windows_winuwp_defs") {
-  defines = [ "FLUTTER_WINUWP 1" ]
+  defines = [ "WINUWP" ]
 }
 
 # The headers are a separate source set since the client wrapper is allowed
@@ -49,6 +50,7 @@ source_set("flutter_windows_headers") {
 }
 
 source_set("flutter_windows_source") {
+  # Common Windows sources.
   sources = [
     "angle_surface_manager.cc",
     "angle_surface_manager.h",
@@ -67,84 +69,43 @@ source_set("flutter_windows_source") {
     "string_conversion.cc",
     "string_conversion.h",
     "system_utils.h",
-    "system_utils_win32.cc",
     "text_input_plugin.cc",
     "text_input_plugin.h",
-    "win32_dpi_utils.cc",
-    "win32_dpi_utils.h",
-    "win32_flutter_window.cc",
-    "win32_flutter_window.h",
-    "win32_platform_handler.cc",
-    "win32_platform_handler.h",
-    "win32_task_runner.cc",
-    "win32_task_runner.h",
-    "win32_window.cc",
-    "win32_window.h",
-    "win32_window_proc_delegate_manager.cc",
-    "win32_window_proc_delegate_manager.h",
     "window_binding_handler.h",
     "window_binding_handler_delegate.h",
     "window_state.h",
   ]
 
-  configs += [
-    "//flutter/shell/platform/common/cpp:desktop_library_implementation",
-    "//third_party/angle:gl_prototypes",
-  ]
-
-  public_configs = [ ":relative_angle_headers" ]
-
-  deps = [
-    ":flutter_windows_headers",
-    "//flutter/shell/platform/common/cpp:common_cpp",
-    "//flutter/shell/platform/common/cpp:common_cpp_input",
-    "//flutter/shell/platform/common/cpp:common_cpp_switches",
-    "//flutter/shell/platform/common/cpp/client_wrapper:client_wrapper",
-    "//flutter/shell/platform/embedder:embedder_as_internal_library",
-    "//flutter/shell/platform/windows/client_wrapper:client_wrapper_windows",
-    "//third_party/angle:libEGL_static",  # the order of libEGL_static and
-                                          # libGLESv2_static is important.. if
-                                          # reversed, will cause a linker error
-                                          # DllMain already defined in
-                                          # LIBCMTD.lib
-    "//third_party/angle:libGLESv2_static",
-    "//third_party/rapidjson",
-  ]
-}
-
-source_set("flutter_winuwp_source") {
-  sources = [
-    "angle_surface_manager.cc",
-    "angle_surface_manager.h",
-    "cursor_handler.cc",
-    "cursor_handler.h",
-    "flutter_project_bundle.cc",
-    "flutter_project_bundle.h",
-    "flutter_windows.cc",
-    "flutter_windows_engine.cc",
-    "flutter_windows_engine.h",
-    "flutter_windows_view.cc",
-    "flutter_windows_view.h",
-    "key_event_handler.cc",
-    "key_event_handler.h",
-    "keyboard_hook_handler.h",
-    "string_conversion.cc",
-    "string_conversion.h",
-    "system_utils.h",
-    "system_utils_winuwp.cc",
-    "text_input_plugin.cc",
-    "text_input_plugin.h",
-    "window_binding_handler.h",
-    "window_binding_handler_delegate.h",
-    "window_state.h",
-  ]
+  # Target-specific sources.
+  if (target_os == "winuwp") {
+    sources += [ "system_utils_winuwp.cc" ]
+  } else {
+    sources += [
+      "system_utils_win32.cc",
+      "win32_dpi_utils.cc",
+      "win32_dpi_utils.h",
+      "win32_flutter_window.cc",
+      "win32_flutter_window.h",
+      "win32_platform_handler.cc",
+      "win32_platform_handler.h",
+      "win32_task_runner.cc",
+      "win32_task_runner.h",
+      "win32_window.cc",
+      "win32_window.h",
+      "win32_window_proc_delegate_manager.cc",
+      "win32_window_proc_delegate_manager.h",
+    ]
+  }
 
   configs += [
     "//flutter/shell/platform/common/cpp:desktop_library_implementation",
     "//third_party/angle:gl_prototypes",
-    ":flutter_windows_winuwp_defs",
   ]
 
+  if (target_os == "winuwp") {
+    configs += [ ":flutter_windows_winuwp_defs" ]
+  }
+
   public_configs = [ ":relative_angle_headers" ]
 
   deps = [
@@ -180,7 +141,7 @@ shared_library("flutter_windows") {
 }
 
 shared_library("flutter_windows_winuwp") {
-  deps = [ ":flutter_winuwp_source" ]
+  deps = [ ":flutter_windows_source" ]
   libs = [ "windowsapp.lib" ]
   public_configs = [ "//flutter:config" ]
 }
@@ -191,27 +152,6 @@ test_fixtures("flutter_windows_fixtures") {
 
 if (target_os == "winuwp") {
   # disabled until the uwp implementation is present
-  # executable("flutter_windows_unittests_winrt") {
-  #   testonly = true
-
-  #   sources = [
-  #     "flutter_project_bundle_unittests.cc",
-  #     "string_conversion_unittests.cc",
-  #     "system_utils_unittests.cc",
-  #   ]
-
-  #   public_configs = [ "//flutter:config" ]
-
-  #     libs = [ "windowsapp.lib" ]
-
-  #   deps = [
-  #     ":flutter_windows_fixtures",
-  #     ":flutter_windows_headers",
-  #     ":flutter_windows_source",
-  #     "//flutter/testing",
-  #     "//third_party/rapidjson",
-  #   ]
-  # }
 } else {
   executable("flutter_windows_unittests") {
     testonly = true
diff --git a/shell/platform/windows/client_wrapper/flutter_view_controller.cc b/shell/platform/windows/client_wrapper/flutter_view_controller.cc
index 65817524f8497..2724b27881f22 100644
--- a/shell/platform/windows/client_wrapper/flutter_view_controller.cc
+++ b/shell/platform/windows/client_wrapper/flutter_view_controller.cc
@@ -29,7 +29,7 @@ FlutterViewController::~FlutterViewController() {
   }
 }
 
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
 std::optional<LRESULT> FlutterViewController::HandleTopLevelWindowProc(
     HWND hwnd,
     UINT message,
diff --git a/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h b/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h
index 916ee4dfd35cf..6a21af0922b81 100644
--- a/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h
+++ b/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h
@@ -46,7 +46,7 @@ class FlutterViewController {
   // Returns the view managed by this controller.
   FlutterView* view() { return view_.get(); }
 
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   // Allows the Flutter engine and any interested plugins an opportunity to
   // handle the given message.
   //
diff --git a/shell/platform/windows/flutter_windows.cc b/shell/platform/windows/flutter_windows.cc
index 29424bfa1c235..49f9cedbbec38 100644
--- a/shell/platform/windows/flutter_windows.cc
+++ b/shell/platform/windows/flutter_windows.cc
@@ -22,13 +22,14 @@
 #include "flutter/shell/platform/windows/flutter_project_bundle.h"
 #include "flutter/shell/platform/windows/flutter_windows_engine.h"
 #include "flutter/shell/platform/windows/flutter_windows_view.h"
-#ifndef FLUTTER_WINUWP
+#include "flutter/shell/platform/windows/window_binding_handler.h"
+#include "flutter/shell/platform/windows/window_state.h"
+
+#ifndef WINUWP
 #include "flutter/shell/platform/windows/win32_dpi_utils.h"       // nogncheck
 #include "flutter/shell/platform/windows/win32_flutter_window.h"  // nogncheck
 #include "flutter/shell/platform/windows/win32_task_runner.h"     // nogncheck
 #endif
-#include "flutter/shell/platform/windows/window_binding_handler.h"
-#include "flutter/shell/platform/windows/window_state.h"
 
 static_assert(FLUTTER_ENGINE_VERSION == 1, "");
 
@@ -58,7 +59,7 @@ FlutterDesktopViewControllerRef FlutterDesktopViewControllerCreate(
     int width,
     int height,
     FlutterDesktopEngineRef engine) {
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   std::unique_ptr<flutter::WindowBindingHandler> window_wrapper =
       std::make_unique<flutter::Win32FlutterWindow>(width, height);
 
@@ -99,7 +100,7 @@ FlutterDesktopViewRef FlutterDesktopViewControllerGetView(
   return HandleForView(controller->view.get());
 }
 
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
 bool FlutterDesktopViewControllerHandleTopLevelWindowProc(
     FlutterDesktopViewControllerRef controller,
     HWND hwnd,
@@ -141,9 +142,10 @@ bool FlutterDesktopEngineRun(FlutterDesktopEngineRef engine,
 }
 
 uint64_t FlutterDesktopEngineProcessMessages(FlutterDesktopEngineRef engine) {
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   return EngineFromHandle(engine)->task_runner()->ProcessTasks().count();
 #else
+  // TODO add WINUWP implementation.
   return 0;
 #endif
 }
@@ -180,7 +182,7 @@ void FlutterDesktopPluginRegistrarRegisterTopLevelWindowProcDelegate(
     FlutterDesktopPluginRegistrarRef registrar,
     FlutterDesktopWindowProcCallback delegate,
     void* user_data) {
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   registrar->engine->window_proc_delegate_manager()
       ->RegisterTopLevelWindowProcDelegate(delegate, user_data);
 #endif
@@ -189,13 +191,13 @@ void FlutterDesktopPluginRegistrarRegisterTopLevelWindowProcDelegate(
 void FlutterDesktopPluginRegistrarUnregisterTopLevelWindowProcDelegate(
     FlutterDesktopPluginRegistrarRef registrar,
     FlutterDesktopWindowProcCallback delegate) {
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   registrar->engine->window_proc_delegate_manager()
       ->UnregisterTopLevelWindowProcDelegate(delegate);
 #endif
 }
 
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
 UINT FlutterDesktopGetDpiForHWND(HWND hwnd) {
   return flutter::GetDpiForHWND(hwnd);
 }
diff --git a/shell/platform/windows/flutter_windows_engine.cc b/shell/platform/windows/flutter_windows_engine.cc
index c083479dc6eda..d5a6f255526d1 100644
--- a/shell/platform/windows/flutter_windows_engine.cc
+++ b/shell/platform/windows/flutter_windows_engine.cc
@@ -91,7 +91,7 @@ FlutterLocale CovertToFlutterLocale(const LanguageInfo& info) {
 
 FlutterWindowsEngine::FlutterWindowsEngine(const FlutterProjectBundle& project)
     : project_(std::make_unique<FlutterProjectBundle>(project)) {
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   task_runner_ = std::make_unique<Win32TaskRunner>(
       GetCurrentThreadId(), [this](const auto* task) {
         if (!engine_) {
@@ -113,7 +113,7 @@ FlutterWindowsEngine::FlutterWindowsEngine(const FlutterProjectBundle& project)
 
   message_dispatcher_ =
       std::make_unique<IncomingMessageDispatcher>(messenger_.get());
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   window_proc_delegate_manager_ =
       std::make_unique<Win32WindowProcDelegateManager>();
 #endif
@@ -155,6 +155,7 @@ bool FlutterWindowsEngine::RunWithEntrypoint(const char* entrypoint) {
       std::back_inserter(entrypoint_argv),
       [](const std::string& arg) -> const char* { return arg.c_str(); });
 
+#ifndef FLUTTER_WINRT
   // Configure task runners.
   FlutterTaskRunnerDescription platform_task_runner = {};
   platform_task_runner.struct_size = sizeof(FlutterTaskRunnerDescription);
@@ -188,7 +189,7 @@ bool FlutterWindowsEngine::RunWithEntrypoint(const char* entrypoint) {
     auto host = static_cast<FlutterWindowsEngine*>(user_data);
     return host->HandlePlatformMessage(engine_message);
   };
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   args.custom_task_runners = &custom_task_runners;
 #endif
   if (aot_data_) {
diff --git a/shell/platform/windows/flutter_windows_engine.h b/shell/platform/windows/flutter_windows_engine.h
index c8c803dcbe21b..8696934e8501f 100644
--- a/shell/platform/windows/flutter_windows_engine.h
+++ b/shell/platform/windows/flutter_windows_engine.h
@@ -13,7 +13,7 @@
 #include "flutter/shell/platform/common/cpp/incoming_message_dispatcher.h"
 #include "flutter/shell/platform/windows/flutter_project_bundle.h"
 #include "flutter/shell/platform/windows/public/flutter_windows.h"
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
 #include "flutter/shell/platform/windows/win32_task_runner.h"  // nogncheck
 #include "flutter/shell/platform/windows/win32_window_proc_delegate_manager.h"  // nogncheck
 #endif
@@ -75,7 +75,7 @@ class FlutterWindowsEngine {
     return message_dispatcher_.get();
   }
 
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   Win32TaskRunner* task_runner() { return task_runner_.get(); }
 
   Win32WindowProcDelegateManager* window_proc_delegate_manager() {
@@ -105,7 +105,7 @@ class FlutterWindowsEngine {
   // The view displaying the content running in this engine, if any.
   FlutterWindowsView* view_ = nullptr;
 
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   // Task runner for tasks posted from the engine.
   std::unique_ptr<Win32TaskRunner> task_runner_;
 #endif
@@ -124,7 +124,7 @@ class FlutterWindowsEngine {
   FlutterDesktopOnPluginRegistrarDestroyed
       plugin_registrar_destruction_callback_;
 
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   // The manager for WindowProc delegate registration and callbacks.
   std::unique_ptr<Win32WindowProcDelegateManager> window_proc_delegate_manager_;
 #endif
diff --git a/shell/platform/windows/flutter_windows_view.cc b/shell/platform/windows/flutter_windows_view.cc
index db47d27ac6da1..4436fced4890d 100644
--- a/shell/platform/windows/flutter_windows_view.cc
+++ b/shell/platform/windows/flutter_windows_view.cc
@@ -39,7 +39,7 @@ void FlutterWindowsView::SetEngine(
       std::make_unique<flutter::KeyEventHandler>(internal_plugin_messenger));
   keyboard_hook_handlers_.push_back(
       std::make_unique<flutter::TextInputPlugin>(internal_plugin_messenger));
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   platform_handler_ = std::make_unique<flutter::PlatformHandler>(
       internal_plugin_messenger, this);
 #endif
diff --git a/shell/platform/windows/flutter_windows_view.h b/shell/platform/windows/flutter_windows_view.h
index c88b8ad2bbe53..462a2285d0879 100644
--- a/shell/platform/windows/flutter_windows_view.h
+++ b/shell/platform/windows/flutter_windows_view.h
@@ -20,7 +20,7 @@
 #include "flutter/shell/platform/windows/keyboard_hook_handler.h"
 #include "flutter/shell/platform/windows/public/flutter_windows.h"
 #include "flutter/shell/platform/windows/text_input_plugin.h"
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
 #include "flutter/shell/platform/windows/win32_platform_handler.h"  // nogncheck
 #endif
 #include "flutter/shell/platform/windows/window_binding_handler.h"
@@ -200,7 +200,7 @@ class FlutterWindowsView : public WindowBindingHandlerDelegate {
   std::vector<std::unique_ptr<flutter::KeyboardHookHandler>>
       keyboard_hook_handlers_;
 
-#ifndef FLUTTER_WINUWP
+#ifndef WINUWP
   // Handler for the flutter/platform channel.
   std::unique_ptr<flutter::PlatformHandler> platform_handler_;
 #endif
diff --git a/shell/platform/windows/public/flutter_windows.h b/shell/platform/windows/public/flutter_windows.h
index d03ff9052c2b3..69269ff339665 100644
--- a/shell/platform/windows/public/flutter_windows.h
+++ b/shell/platform/windows/public/flutter_windows.h
@@ -92,7 +92,7 @@ FLUTTER_EXPORT FlutterDesktopEngineRef FlutterDesktopViewControllerGetEngine(
 FLUTTER_EXPORT FlutterDesktopViewRef
 FlutterDesktopViewControllerGetView(FlutterDesktopViewControllerRef controller);
 
-  #ifndef FLUTTER_WINUWP
+  #ifndef WINUWP
 // Allows the Flutter engine and any interested plugins an opportunity to
 // handle the given message.
 //

From 925c5715204dab9abcf46a0c3019120e1340c38a Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Sat, 31 Oct 2020 11:35:51 -0700
Subject: [PATCH 03/19] Update licenses

---
 ci/licenses_golden/licenses_flutter | 1 +
 1 file changed, 1 insertion(+)

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index f13271aa91373..25b78b13efa30 100755
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -1412,6 +1412,7 @@ FILE: ../../../flutter/shell/platform/windows/string_conversion_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/system_utils.h
 FILE: ../../../flutter/shell/platform/windows/system_utils_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/system_utils_win32.cc
+FILE: ../../../flutter/shell/platform/windows/system_utils_winuwp.cc
 FILE: ../../../flutter/shell/platform/windows/text_input_plugin.cc
 FILE: ../../../flutter/shell/platform/windows/text_input_plugin.h
 FILE: ../../../flutter/shell/platform/windows/win32_dpi_utils.cc

From 8ec92beb5965eb830a620901819e56c8b09e920a Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Sat, 31 Oct 2020 12:23:20 -0700
Subject: [PATCH 04/19] Move the flutter_windows_winuwp_defs to buildroot

---
 shell/platform/windows/BUILD.gn                | 10 ++--------
 shell/platform/windows/client_wrapper/BUILD.gn |  2 +-
 2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index 1bf1ac0302947..919ccc0296288 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -21,12 +21,6 @@ config("relative_flutter_windows_headers") {
   include_dirs = [ "public" ]
 }
 
-# TODO: Move to builtroot build/config/win/BUILD.gn when the UWP compliant change to that project lands.
-# When OS target is WinUWP use WINUWP as the preprocessor flag to conditionalize.
-config("flutter_windows_winuwp_defs") {
-  defines = [ "WINUWP" ]
-}
-
 # The headers are a separate source set since the client wrapper is allowed
 # to depend on the public headers, but none of the rest of the code.
 source_set("flutter_windows_headers") {
@@ -38,7 +32,7 @@ source_set("flutter_windows_headers") {
   if (target_os == "winuwp") {
     configs += [
       "//flutter/shell/platform/common/cpp:desktop_library_implementation",
-      ":flutter_windows_winuwp_defs",
+      "//build/config/win:flutter_windows_winuwp_defs",
     ]
   } else {
     configs +=
@@ -103,7 +97,7 @@ source_set("flutter_windows_source") {
   ]
 
   if (target_os == "winuwp") {
-    configs += [ ":flutter_windows_winuwp_defs" ]
+    configs += [ "//build/config/win:flutter_windows_winuwp_defs" ]
   }
 
   public_configs = [ ":relative_angle_headers" ]
diff --git a/shell/platform/windows/client_wrapper/BUILD.gn b/shell/platform/windows/client_wrapper/BUILD.gn
index 155d87575e74f..1f96788d5c2b1 100644
--- a/shell/platform/windows/client_wrapper/BUILD.gn
+++ b/shell/platform/windows/client_wrapper/BUILD.gn
@@ -41,7 +41,7 @@ source_set("client_wrapper_windows") {
 
   configs += [
     "//flutter/shell/platform/common/cpp:desktop_library_implementation",
-    "//flutter/shell/platform/windows:flutter_windows_winuwp_defs",
+    "//build/config/win:flutter_windows_winuwp_defs",
   ]
 
   public_configs = [

From 642332dcbecb92262dce31767946c7a25f011386 Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Thu, 5 Nov 2020 06:11:59 -0800
Subject: [PATCH 05/19] CR Feedback: UWP ifdef applied automatically by
 buildroot

---
 shell/platform/windows/BUILD.gn                | 5 -----
 shell/platform/windows/client_wrapper/BUILD.gn | 1 -
 2 files changed, 6 deletions(-)

diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index 919ccc0296288..7070243568d77 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -32,7 +32,6 @@ source_set("flutter_windows_headers") {
   if (target_os == "winuwp") {
     configs += [
       "//flutter/shell/platform/common/cpp:desktop_library_implementation",
-      "//build/config/win:flutter_windows_winuwp_defs",
     ]
   } else {
     configs +=
@@ -96,10 +95,6 @@ source_set("flutter_windows_source") {
     "//third_party/angle:gl_prototypes",
   ]
 
-  if (target_os == "winuwp") {
-    configs += [ "//build/config/win:flutter_windows_winuwp_defs" ]
-  }
-
   public_configs = [ ":relative_angle_headers" ]
 
   deps = [
diff --git a/shell/platform/windows/client_wrapper/BUILD.gn b/shell/platform/windows/client_wrapper/BUILD.gn
index 1f96788d5c2b1..15fc0d4c16d33 100644
--- a/shell/platform/windows/client_wrapper/BUILD.gn
+++ b/shell/platform/windows/client_wrapper/BUILD.gn
@@ -41,7 +41,6 @@ source_set("client_wrapper_windows") {
 
   configs += [
     "//flutter/shell/platform/common/cpp:desktop_library_implementation",
-    "//build/config/win:flutter_windows_winuwp_defs",
   ]
 
   public_configs = [

From 0607fa02005c0b26f5e0ad028fbca5557d172c62 Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Thu, 5 Nov 2020 07:01:57 -0800
Subject: [PATCH 06/19] CR feedback: split flutter_windows.cc

---
 ci/licenses_golden/licenses_flutter           |  2 +
 shell/platform/windows/BUILD.gn               |  2 +
 shell/platform/windows/flutter_windows.cc     | 93 ------------------
 .../platform/windows/flutter_windows_win32.cc | 95 +++++++++++++++++++
 .../windows/flutter_windows_winuwp.cc         | 45 +++++++++
 5 files changed, 144 insertions(+), 93 deletions(-)
 create mode 100644 shell/platform/windows/flutter_windows_win32.cc
 create mode 100644 shell/platform/windows/flutter_windows_winuwp.cc

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index 25b78b13efa30..a7e9ac9bd0ec2 100755
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -1398,6 +1398,8 @@ FILE: ../../../flutter/shell/platform/windows/flutter_project_bundle.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_project_bundle.h
 FILE: ../../../flutter/shell/platform/windows/flutter_project_bundle_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_windows.cc
+FILE: ../../../flutter/shell/platform/windows/flutter_windows_win32.cc
+FILE: ../../../flutter/shell/platform/windows/flutter_windows_winuwp.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_windows_engine.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_windows_engine.h
 FILE: ../../../flutter/shell/platform/windows/flutter_windows_view.cc
diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index 7070243568d77..cbf24ea03da0d 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -71,9 +71,11 @@ source_set("flutter_windows_source") {
 
   # Target-specific sources.
   if (target_os == "winuwp") {
+    sources += [ "flutter_windows_winuwp.cc" ]
     sources += [ "system_utils_winuwp.cc" ]
   } else {
     sources += [
+      "flutter_windows_win32.cc",
       "system_utils_win32.cc",
       "win32_dpi_utils.cc",
       "win32_dpi_utils.h",
diff --git a/shell/platform/windows/flutter_windows.cc b/shell/platform/windows/flutter_windows.cc
index 49f9cedbbec38..f15f2bf6636dd 100644
--- a/shell/platform/windows/flutter_windows.cc
+++ b/shell/platform/windows/flutter_windows.cc
@@ -25,12 +25,6 @@
 #include "flutter/shell/platform/windows/window_binding_handler.h"
 #include "flutter/shell/platform/windows/window_state.h"
 
-#ifndef WINUWP
-#include "flutter/shell/platform/windows/win32_dpi_utils.h"       // nogncheck
-#include "flutter/shell/platform/windows/win32_flutter_window.h"  // nogncheck
-#include "flutter/shell/platform/windows/win32_task_runner.h"     // nogncheck
-#endif
-
 static_assert(FLUTTER_ENGINE_VERSION == 1, "");
 
 // Returns the engine corresponding to the given opaque API handle.
@@ -55,36 +49,6 @@ static FlutterDesktopViewRef HandleForView(flutter::FlutterWindowsView* view) {
   return reinterpret_cast<FlutterDesktopViewRef>(view);
 }
 
-FlutterDesktopViewControllerRef FlutterDesktopViewControllerCreate(
-    int width,
-    int height,
-    FlutterDesktopEngineRef engine) {
-#ifndef WINUWP
-  std::unique_ptr<flutter::WindowBindingHandler> window_wrapper =
-      std::make_unique<flutter::Win32FlutterWindow>(width, height);
-
-  auto state = std::make_unique<FlutterDesktopViewControllerState>();
-  state->view =
-      std::make_unique<flutter::FlutterWindowsView>(std::move(window_wrapper));
-  state->view->CreateRenderSurface();
-
-  // Take ownership of the engine, starting it if necessary.
-  state->view->SetEngine(
-      std::unique_ptr<flutter::FlutterWindowsEngine>(EngineFromHandle(engine)));
-  if (!state->view->GetEngine()->running()) {
-    if (!state->view->GetEngine()->RunWithEntrypoint(nullptr)) {
-      return nullptr;
-    }
-  }
-
-  // Must happen after engine is running.
-  state->view->SendInitialBounds();
-  return state.release();
-#else
-  return nullptr;
-#endif
-}
-
 void FlutterDesktopViewControllerDestroy(
     FlutterDesktopViewControllerRef controller) {
   delete controller;
@@ -100,25 +64,6 @@ FlutterDesktopViewRef FlutterDesktopViewControllerGetView(
   return HandleForView(controller->view.get());
 }
 
-#ifndef WINUWP
-bool FlutterDesktopViewControllerHandleTopLevelWindowProc(
-    FlutterDesktopViewControllerRef controller,
-    HWND hwnd,
-    UINT message,
-    WPARAM wparam,
-    LPARAM lparam,
-    LRESULT* result) {
-  std::optional<LRESULT> delegate_result =
-      controller->view->GetEngine()
-          ->window_proc_delegate_manager()
-          ->OnTopLevelWindowProc(hwnd, message, wparam, lparam);
-  if (delegate_result) {
-    *result = *delegate_result;
-  }
-  return delegate_result.has_value();
-}
-#endif
-
 FlutterDesktopEngineRef FlutterDesktopEngineCreate(
     const FlutterDesktopEngineProperties& engine_properties) {
   flutter::FlutterProjectBundle project(engine_properties);
@@ -141,15 +86,6 @@ bool FlutterDesktopEngineRun(FlutterDesktopEngineRef engine,
   return EngineFromHandle(engine)->RunWithEntrypoint(entry_point);
 }
 
-uint64_t FlutterDesktopEngineProcessMessages(FlutterDesktopEngineRef engine) {
-#ifndef WINUWP
-  return EngineFromHandle(engine)->task_runner()->ProcessTasks().count();
-#else
-  // TODO add WINUWP implementation.
-  return 0;
-#endif
-}
-
 void FlutterDesktopEngineReloadSystemFonts(FlutterDesktopEngineRef engine) {
   FlutterEngineReloadSystemFonts(EngineFromHandle(engine)->engine());
 }
@@ -178,35 +114,6 @@ FlutterDesktopViewRef FlutterDesktopPluginRegistrarGetView(
   return HandleForView(registrar->engine->view());
 }
 
-void FlutterDesktopPluginRegistrarRegisterTopLevelWindowProcDelegate(
-    FlutterDesktopPluginRegistrarRef registrar,
-    FlutterDesktopWindowProcCallback delegate,
-    void* user_data) {
-#ifndef WINUWP
-  registrar->engine->window_proc_delegate_manager()
-      ->RegisterTopLevelWindowProcDelegate(delegate, user_data);
-#endif
-}
-
-void FlutterDesktopPluginRegistrarUnregisterTopLevelWindowProcDelegate(
-    FlutterDesktopPluginRegistrarRef registrar,
-    FlutterDesktopWindowProcCallback delegate) {
-#ifndef WINUWP
-  registrar->engine->window_proc_delegate_manager()
-      ->UnregisterTopLevelWindowProcDelegate(delegate);
-#endif
-}
-
-#ifndef WINUWP
-UINT FlutterDesktopGetDpiForHWND(HWND hwnd) {
-  return flutter::GetDpiForHWND(hwnd);
-}
-
-UINT FlutterDesktopGetDpiForMonitor(HMONITOR monitor) {
-  return flutter::GetDpiForMonitor(monitor);
-}
-#endif
-
 void FlutterDesktopResyncOutputStreams() {
   FILE* unused;
   if (freopen_s(&unused, "CONOUT$", "w", stdout)) {
diff --git a/shell/platform/windows/flutter_windows_win32.cc b/shell/platform/windows/flutter_windows_win32.cc
new file mode 100644
index 0000000000000..a02ce37720dd8
--- /dev/null
+++ b/shell/platform/windows/flutter_windows_win32.cc
@@ -0,0 +1,95 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/windows/public/flutter_windows.h"
+
+#include <io.h>
+
+#include <algorithm>
+#include <cassert>
+#include <chrono>
+#include <cstdlib>
+#include <filesystem>
+#include <iostream>
+#include <memory>
+#include <vector>
+
+#include "flutter/shell/platform/windows/win32_dpi_utils.h"
+#include "flutter/shell/platform/windows/win32_flutter_window.h"
+
+// Returns the engine corresponding to the given opaque API handle.
+static flutter::FlutterWindowsEngine* EngineFromHandle(
+    FlutterDesktopEngineRef ref) {
+  return reinterpret_cast<flutter::FlutterWindowsEngine*>(ref);
+}
+
+FlutterDesktopViewControllerRef FlutterDesktopViewControllerCreate(
+    int width,
+    int height,
+    FlutterDesktopEngineRef engine) {
+  std::unique_ptr<flutter::WindowBindingHandler> window_wrapper =
+      std::make_unique<flutter::Win32FlutterWindow>(width, height);
+
+  auto state = std::make_unique<FlutterDesktopViewControllerState>();
+  state->view =
+      std::make_unique<flutter::FlutterWindowsView>(std::move(window_wrapper));
+  state->view->CreateRenderSurface();
+
+  // Take ownership of the engine, starting it if necessary.
+  state->view->SetEngine(
+      std::unique_ptr<flutter::FlutterWindowsEngine>(EngineFromHandle(engine)));
+  if (!state->view->GetEngine()->running()) {
+    if (!state->view->GetEngine()->RunWithEntrypoint(nullptr)) {
+      return nullptr;
+    }
+  }
+
+  // Must happen after engine is running.
+  state->view->SendInitialBounds();
+  return state.release();
+}
+
+bool FlutterDesktopViewControllerHandleTopLevelWindowProc(
+    FlutterDesktopViewControllerRef controller,
+    HWND hwnd,
+    UINT message,
+    WPARAM wparam,
+    LPARAM lparam,
+    LRESULT* result) {
+  std::optional<LRESULT> delegate_result =
+      controller->view->GetEngine()
+          ->window_proc_delegate_manager()
+          ->OnTopLevelWindowProc(hwnd, message, wparam, lparam);
+  if (delegate_result) {
+    *result = *delegate_result;
+  }
+  return delegate_result.has_value();
+}
+
+uint64_t FlutterDesktopEngineProcessMessages(FlutterDesktopEngineRef engine) {
+  return EngineFromHandle(engine)->task_runner()->ProcessTasks().count();
+}
+
+void FlutterDesktopPluginRegistrarRegisterTopLevelWindowProcDelegate(
+    FlutterDesktopPluginRegistrarRef registrar,
+    FlutterDesktopWindowProcCallback delegate,
+    void* user_data) {
+  registrar->engine->window_proc_delegate_manager()
+      ->RegisterTopLevelWindowProcDelegate(delegate, user_data);
+}
+
+void FlutterDesktopPluginRegistrarUnregisterTopLevelWindowProcDelegate(
+    FlutterDesktopPluginRegistrarRef registrar,
+    FlutterDesktopWindowProcCallback delegate) {
+  registrar->engine->window_proc_delegate_manager()
+      ->UnregisterTopLevelWindowProcDelegate(delegate);
+}
+
+UINT FlutterDesktopGetDpiForHWND(HWND hwnd) {
+  return flutter::GetDpiForHWND(hwnd);
+}
+
+UINT FlutterDesktopGetDpiForMonitor(HMONITOR monitor) {
+  return flutter::GetDpiForMonitor(monitor);
+}
diff --git a/shell/platform/windows/flutter_windows_winuwp.cc b/shell/platform/windows/flutter_windows_winuwp.cc
new file mode 100644
index 0000000000000..35cd27e25f661
--- /dev/null
+++ b/shell/platform/windows/flutter_windows_winuwp.cc
@@ -0,0 +1,45 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/windows/public/flutter_windows.h"
+
+#include <io.h>
+
+#include <algorithm>
+#include <cassert>
+#include <chrono>
+#include <cstdlib>
+#include <filesystem>
+#include <iostream>
+#include <memory>
+#include <vector>
+
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/plugin_registrar.h"
+#include "flutter/shell/platform/common/cpp/incoming_message_dispatcher.h"
+
+FlutterDesktopViewControllerRef FlutterDesktopViewControllerCreate(
+    int width,
+    int height,
+    FlutterDesktopEngineRef engine) {
+  // TODO add WINUWP implementation.
+  return nullptr;
+}
+
+uint64_t FlutterDesktopEngineProcessMessages(FlutterDesktopEngineRef engine) {
+  // TODO add WINUWP implementation.
+  return 0;
+}
+
+void FlutterDesktopPluginRegistrarRegisterTopLevelWindowProcDelegate(
+    FlutterDesktopPluginRegistrarRef registrar,
+    FlutterDesktopWindowProcCallback delegate,
+    void* user_data) {
+  // TODO add WINUWP implementation.
+}
+
+void FlutterDesktopPluginRegistrarUnregisterTopLevelWindowProcDelegate(
+    FlutterDesktopPluginRegistrarRef registrar,
+    FlutterDesktopWindowProcCallback delegate) {
+  // TODO add WINUWP implementation.
+}

From 28cfc6ac2b7c08468310334befa3fca681aa53f3 Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Sat, 7 Nov 2020 06:14:33 -0800
Subject: [PATCH 07/19] CR Feedback

---
 DEPS                                          |  2 +-
 ci/licenses_golden/licenses_flutter           |  3 +
 shell/platform/windows/BUILD.gn               | 14 +++--
 .../windows/client_wrapper/flutter_engine.cc  |  2 +
 .../windows/flutter_windows_engine.cc         | 23 ++++++--
 .../platform/windows/flutter_windows_engine.h | 14 +++--
 .../platform/windows/flutter_windows_win32.cc |  6 +-
 .../platform/windows/public/flutter_windows.h |  2 +
 shell/platform/windows/task_runner.h          | 32 +++++++++++
 shell/platform/windows/win32_task_runner.h    | 14 +++--
 shell/platform/windows/winrt_task_runner.cc   | 43 +++++++++++++++
 shell/platform/windows/winrt_task_runner.h    | 55 +++++++++++++++++++
 12 files changed, 185 insertions(+), 25 deletions(-)
 create mode 100644 shell/platform/windows/task_runner.h
 create mode 100644 shell/platform/windows/winrt_task_runner.cc
 create mode 100644 shell/platform/windows/winrt_task_runner.h

diff --git a/DEPS b/DEPS
index 5276ad26c2ac9..b21005385a275 100644
--- a/DEPS
+++ b/DEPS
@@ -105,7 +105,7 @@ allowed_hosts = [
 ]
 
 deps = {
-  'src': 'https://github.com/flutter/buildroot.git' + '@' + '9184ff0695be1b3e4bb20cf64efcfa56daa0a3c0',
+  'src': 'https://github.com/flutter/buildroot.git' + '@' + 'e6c83ddcc5a2d1ca9bf727d4aae13c2cf8d9999e',
 
    # Fuchsia compatibility
    #
diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index a7e9ac9bd0ec2..0430d0143f358 100755
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -1415,6 +1415,7 @@ FILE: ../../../flutter/shell/platform/windows/system_utils.h
 FILE: ../../../flutter/shell/platform/windows/system_utils_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/system_utils_win32.cc
 FILE: ../../../flutter/shell/platform/windows/system_utils_winuwp.cc
+FILE: ../../../flutter/shell/platform/windows/task_runner.h
 FILE: ../../../flutter/shell/platform/windows/text_input_plugin.cc
 FILE: ../../../flutter/shell/platform/windows/text_input_plugin.h
 FILE: ../../../flutter/shell/platform/windows/win32_dpi_utils.cc
@@ -1436,6 +1437,8 @@ FILE: ../../../flutter/shell/platform/windows/win32_window_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/window_binding_handler.h
 FILE: ../../../flutter/shell/platform/windows/window_binding_handler_delegate.h
 FILE: ../../../flutter/shell/platform/windows/window_state.h
+FILE: ../../../flutter/shell/platform/windows/winrt_task_runner.cc
+FILE: ../../../flutter/shell/platform/windows/winrt_task_runner.h
 FILE: ../../../flutter/shell/profiling/sampling_profiler.cc
 FILE: ../../../flutter/shell/profiling/sampling_profiler.h
 FILE: ../../../flutter/shell/version/version.cc
diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index cbf24ea03da0d..4eab309f4a9ee 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -30,9 +30,8 @@ source_set("flutter_windows_headers") {
       [ "//flutter/shell/platform/common/cpp:common_cpp_library_headers" ]
 
   if (target_os == "winuwp") {
-    configs += [
-      "//flutter/shell/platform/common/cpp:desktop_library_implementation",
-    ]
+    configs +=
+        [ "//flutter/shell/platform/common/cpp:desktop_library_implementation" ]
   } else {
     configs +=
         [ "//flutter/shell/platform/common/cpp:desktop_library_implementation" ]
@@ -62,6 +61,7 @@ source_set("flutter_windows_source") {
     "string_conversion.cc",
     "string_conversion.h",
     "system_utils.h",
+    "task_runner.h",
     "text_input_plugin.cc",
     "text_input_plugin.h",
     "window_binding_handler.h",
@@ -71,8 +71,12 @@ source_set("flutter_windows_source") {
 
   # Target-specific sources.
   if (target_os == "winuwp") {
-    sources += [ "flutter_windows_winuwp.cc" ]
-    sources += [ "system_utils_winuwp.cc" ]
+    sources += [
+      "flutter_windows_winuwp.cc",
+      "system_utils_winuwp.cc",
+      "winrt_task_runner.cc",
+      "winrt_task_runner.h",
+    ]
   } else {
     sources += [
       "flutter_windows_win32.cc",
diff --git a/shell/platform/windows/client_wrapper/flutter_engine.cc b/shell/platform/windows/client_wrapper/flutter_engine.cc
index a1fc0c4659066..12ca29743c695 100644
--- a/shell/platform/windows/client_wrapper/flutter_engine.cc
+++ b/shell/platform/windows/client_wrapper/flutter_engine.cc
@@ -64,9 +64,11 @@ void FlutterEngine::ShutDown() {
   engine_ = nullptr;
 }
 
+#ifndef WINUWP
 std::chrono::nanoseconds FlutterEngine::ProcessMessages() {
   return std::chrono::nanoseconds(FlutterDesktopEngineProcessMessages(engine_));
 }
+#endif
 
 void FlutterEngine::ReloadSystemFonts() {
   FlutterDesktopEngineReloadSystemFonts(engine_);
diff --git a/shell/platform/windows/flutter_windows_engine.cc b/shell/platform/windows/flutter_windows_engine.cc
index d5a6f255526d1..a62c461a63264 100644
--- a/shell/platform/windows/flutter_windows_engine.cc
+++ b/shell/platform/windows/flutter_windows_engine.cc
@@ -12,6 +12,7 @@
 #include "flutter/shell/platform/windows/flutter_windows_view.h"
 #include "flutter/shell/platform/windows/string_conversion.h"
 #include "flutter/shell/platform/windows/system_utils.h"
+#include "flutter/shell/platform/windows/task_runner.h"
 
 namespace flutter {
 
@@ -103,6 +104,18 @@ FlutterWindowsEngine::FlutterWindowsEngine(const FlutterProjectBundle& project)
           std::cerr << "Failed to post an engine task." << std::endl;
         }
       });
+#else
+  task_runner_ = std::make_unique<WinrtTaskRunner>(
+      GetCurrentThreadId(), [this](const auto* task) {
+        if (!engine_) {
+          std::cerr << "Cannot post an engine task when engine is not running."
+                    << std::endl;
+          return;
+        }
+        if (FlutterEngineRunTask(engine_, task) != kSuccess) {
+          std::cerr << "Failed to post an engine task." << std::endl;
+        }
+      });
 #endif
 
   // Set up the legacy structs backing the API handles.
@@ -155,24 +168,22 @@ bool FlutterWindowsEngine::RunWithEntrypoint(const char* entrypoint) {
       std::back_inserter(entrypoint_argv),
       [](const std::string& arg) -> const char* { return arg.c_str(); });
 
-#ifndef FLUTTER_WINRT
   // Configure task runners.
   FlutterTaskRunnerDescription platform_task_runner = {};
   platform_task_runner.struct_size = sizeof(FlutterTaskRunnerDescription);
   platform_task_runner.user_data = task_runner_.get();
   platform_task_runner.runs_task_on_current_thread_callback =
       [](void* user_data) -> bool {
-    return static_cast<Win32TaskRunner*>(user_data)->RunsTasksOnCurrentThread();
+    return static_cast<TaskRunner*>(user_data)->RunsTasksOnCurrentThread();
   };
   platform_task_runner.post_task_callback = [](FlutterTask task,
                                                uint64_t target_time_nanos,
                                                void* user_data) -> void {
-    static_cast<Win32TaskRunner*>(user_data)->PostTask(task, target_time_nanos);
+    static_cast<TaskRunner*>(user_data)->PostTask(task, target_time_nanos);
   };
   FlutterCustomTaskRunners custom_task_runners = {};
   custom_task_runners.struct_size = sizeof(FlutterCustomTaskRunners);
   custom_task_runners.platform_task_runner = &platform_task_runner;
-#endif
 
   FlutterProjectArgs args = {};
   args.struct_size = sizeof(FlutterProjectArgs);
@@ -189,9 +200,9 @@ bool FlutterWindowsEngine::RunWithEntrypoint(const char* entrypoint) {
     auto host = static_cast<FlutterWindowsEngine*>(user_data);
     return host->HandlePlatformMessage(engine_message);
   };
-#ifndef WINUWP
+
   args.custom_task_runners = &custom_task_runners;
-#endif
+
   if (aot_data_) {
     args.aot_data = aot_data_.get();
   }
diff --git a/shell/platform/windows/flutter_windows_engine.h b/shell/platform/windows/flutter_windows_engine.h
index 8696934e8501f..03f549e300642 100644
--- a/shell/platform/windows/flutter_windows_engine.h
+++ b/shell/platform/windows/flutter_windows_engine.h
@@ -13,11 +13,15 @@
 #include "flutter/shell/platform/common/cpp/incoming_message_dispatcher.h"
 #include "flutter/shell/platform/windows/flutter_project_bundle.h"
 #include "flutter/shell/platform/windows/public/flutter_windows.h"
+#include "flutter/shell/platform/windows/task_runner.h"
+#include "flutter/shell/platform/windows/window_state.h"
+
 #ifndef WINUWP
 #include "flutter/shell/platform/windows/win32_task_runner.h"  // nogncheck
 #include "flutter/shell/platform/windows/win32_window_proc_delegate_manager.h"  // nogncheck
+#else
+#include "flutter/shell/platform/windows/winrt_task_runner.h"  // nogncheck
 #endif
-#include "flutter/shell/platform/windows/window_state.h"
 
 namespace flutter {
 
@@ -75,9 +79,9 @@ class FlutterWindowsEngine {
     return message_dispatcher_.get();
   }
 
-#ifndef WINUWP
-  Win32TaskRunner* task_runner() { return task_runner_.get(); }
+  TaskRunner* task_runner() { return task_runner_.get(); }
 
+#ifndef WINUWP
   Win32WindowProcDelegateManager* window_proc_delegate_manager() {
     return window_proc_delegate_manager_.get();
   }
@@ -105,10 +109,8 @@ class FlutterWindowsEngine {
   // The view displaying the content running in this engine, if any.
   FlutterWindowsView* view_ = nullptr;
 
-#ifndef WINUWP
   // Task runner for tasks posted from the engine.
-  std::unique_ptr<Win32TaskRunner> task_runner_;
-#endif
+  std::unique_ptr<TaskRunner> task_runner_;
 
   // The plugin messenger handle given to API clients.
   std::unique_ptr<FlutterDesktopMessenger> messenger_;
diff --git a/shell/platform/windows/flutter_windows_win32.cc b/shell/platform/windows/flutter_windows_win32.cc
index a02ce37720dd8..45dcf818413b7 100644
--- a/shell/platform/windows/flutter_windows_win32.cc
+++ b/shell/platform/windows/flutter_windows_win32.cc
@@ -17,6 +17,7 @@
 
 #include "flutter/shell/platform/windows/win32_dpi_utils.h"
 #include "flutter/shell/platform/windows/win32_flutter_window.h"
+#include "flutter/shell/platform/windows/win32_task_runner.h"
 
 // Returns the engine corresponding to the given opaque API handle.
 static flutter::FlutterWindowsEngine* EngineFromHandle(
@@ -68,7 +69,10 @@ bool FlutterDesktopViewControllerHandleTopLevelWindowProc(
 }
 
 uint64_t FlutterDesktopEngineProcessMessages(FlutterDesktopEngineRef engine) {
-  return EngineFromHandle(engine)->task_runner()->ProcessTasks().count();
+  return static_cast<flutter::Win32TaskRunner*>(
+             EngineFromHandle(engine)->task_runner())
+      ->ProcessTasks()
+      .count();
 }
 
 void FlutterDesktopPluginRegistrarRegisterTopLevelWindowProcDelegate(
diff --git a/shell/platform/windows/public/flutter_windows.h b/shell/platform/windows/public/flutter_windows.h
index 69269ff339665..54cb5d905e338 100644
--- a/shell/platform/windows/public/flutter_windows.h
+++ b/shell/platform/windows/public/flutter_windows.h
@@ -134,6 +134,7 @@ FLUTTER_EXPORT bool FlutterDesktopEngineDestroy(FlutterDesktopEngineRef engine);
 FLUTTER_EXPORT bool FlutterDesktopEngineRun(FlutterDesktopEngineRef engine,
                                             const char* entry_point);
 
+#ifndef WINUWP
 // Processes any pending events in the Flutter engine, and returns the
 // number of nanoseconds until the next scheduled event (or max, if none).
 //
@@ -142,6 +143,7 @@ FLUTTER_EXPORT bool FlutterDesktopEngineRun(FlutterDesktopEngineRef engine,
 // last return value from this function.
 FLUTTER_EXPORT uint64_t
 FlutterDesktopEngineProcessMessages(FlutterDesktopEngineRef engine);
+#endif
 
 FLUTTER_EXPORT void FlutterDesktopEngineReloadSystemFonts(
     FlutterDesktopEngineRef engine);
diff --git a/shell/platform/windows/task_runner.h b/shell/platform/windows/task_runner.h
new file mode 100644
index 0000000000000..61f33f2361d38
--- /dev/null
+++ b/shell/platform/windows/task_runner.h
@@ -0,0 +1,32 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_TASK_RUNNER_H_
+#define FLUTTER_SHELL_PLATFORM_WINDOWS_TASK_RUNNER_H_
+
+#include <windows.h>
+
+#include <chrono>
+#include <memory>
+
+#include "flutter/shell/platform/embedder/embedder.h"
+
+namespace flutter {
+
+// Abstract custom task runner for scheduling custom tasks.
+class TaskRunner {
+ public:
+  virtual ~TaskRunner() = default;
+
+  // Returns if the current thread is the UI thread.
+  virtual bool RunsTasksOnCurrentThread() const = 0;
+
+  // Post a Flutter engine tasks to the event loop for delayed execution.
+  virtual void PostTask(FlutterTask flutter_task,
+                        uint64_t flutter_target_time_nanos) = 0;
+};
+
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_TASK_RUNNER_H_
diff --git a/shell/platform/windows/win32_task_runner.h b/shell/platform/windows/win32_task_runner.h
index a35490a8563b1..ddfe3b3d7c2f7 100644
--- a/shell/platform/windows/win32_task_runner.h
+++ b/shell/platform/windows/win32_task_runner.h
@@ -15,27 +15,29 @@
 #include <thread>
 
 #include "flutter/shell/platform/embedder/embedder.h"
+#include "flutter/shell/platform/windows/task_runner.h"
 
 namespace flutter {
 
 // A custom task runner that integrates with user32 GetMessage semantics so that
 // host app can own its own message loop and flutter still gets to process
 // tasks on a timely basis.
-class Win32TaskRunner {
+class Win32TaskRunner : public TaskRunner {
  public:
   using TaskExpiredCallback = std::function<void(const FlutterTask*)>;
   Win32TaskRunner(DWORD main_thread_id,
                   const TaskExpiredCallback& on_task_expired);
 
-  ~Win32TaskRunner();
+  virtual ~Win32TaskRunner();
 
-  // Returns if the current thread is the thread used by the win32 event loop.
-  bool RunsTasksOnCurrentThread() const;
+  // |RunsTasksOnCurrentThread|
+  bool RunsTasksOnCurrentThread() const override;
 
   std::chrono::nanoseconds ProcessTasks();
 
-  // Post a Flutter engine tasks to the event loop for delayed execution.
-  void PostTask(FlutterTask flutter_task, uint64_t flutter_target_time_nanos);
+  // |PostTask|
+  void PostTask(FlutterTask flutter_task,
+                uint64_t flutter_target_time_nanos) override;
 
  private:
   using TaskTimePoint = std::chrono::steady_clock::time_point;
diff --git a/shell/platform/windows/winrt_task_runner.cc b/shell/platform/windows/winrt_task_runner.cc
new file mode 100644
index 0000000000000..56374a57cf5a7
--- /dev/null
+++ b/shell/platform/windows/winrt_task_runner.cc
@@ -0,0 +1,43 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/windows/winrt_task_runner.h"
+
+#include <atomic>
+#include <utility>
+
+namespace flutter {
+
+WinrtTaskRunner::WinrtTaskRunner(DWORD main_thread_id,
+                                 const TaskExpiredCallback& on_task_expired)
+    : main_thread_id_(main_thread_id),
+      on_task_expired_(std::move(on_task_expired)) {
+  dispatcher_ =
+      winrt::Windows::UI::Core::CoreWindow::GetForCurrentThread().Dispatcher();
+}
+
+WinrtTaskRunner::~WinrtTaskRunner() = default;
+
+bool WinrtTaskRunner::RunsTasksOnCurrentThread() const {
+  return GetCurrentThreadId() == main_thread_id_;
+}
+
+WinrtTaskRunner::TaskTimePoint WinrtTaskRunner::TimePointFromFlutterTime(
+    uint64_t flutter_target_time_nanos) {
+  const auto now = TaskTimePoint::clock::now();
+  const auto flutter_duration =
+      flutter_target_time_nanos - FlutterEngineGetCurrentTime();
+  return now + std::chrono::nanoseconds(flutter_duration);
+}
+
+void WinrtTaskRunner::PostTask(FlutterTask flutter_task,
+                               uint64_t flutter_target_time_nanos) {
+  // TODO: consider waiting on threadpool thread until target time
+
+  dispatcher_.RunAsync(
+      winrt::Windows::UI::Core::CoreDispatcherPriority::Normal,
+      [this, flutter_task]() { on_task_expired_(&flutter_task); });
+}
+
+}  // namespace flutter
diff --git a/shell/platform/windows/winrt_task_runner.h b/shell/platform/windows/winrt_task_runner.h
new file mode 100644
index 0000000000000..79ee79c26d454
--- /dev/null
+++ b/shell/platform/windows/winrt_task_runner.h
@@ -0,0 +1,55 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_WINRT_TASK_RUNNER_H_
+#define FLUTTER_SHELL_PLATFORM_WINDOWS_WINRT_TASK_RUNNER_H_
+
+#include <windows.h>
+
+#include <winrt/Windows.UI.Core.h>
+
+#include <chrono>
+#include <functional>
+#include <thread>
+
+#include "flutter/shell/platform/embedder/embedder.h"
+#include "flutter/shell/platform/windows/task_runner.h"
+
+namespace flutter {
+
+// A custom task runner that uses a CoreDispatcher to schedule
+// flutter tasks.
+class WinrtTaskRunner : public TaskRunner {
+ public:
+  using TaskExpiredCallback = std::function<void(const FlutterTask*)>;
+  WinrtTaskRunner(DWORD main_thread_id,
+                  const TaskExpiredCallback& on_task_expired);
+
+  ~WinrtTaskRunner();
+
+  // |RunsTasksOnCurrentThread|
+  bool RunsTasksOnCurrentThread() const override;
+
+  // |PostTask|
+  void PostTask(FlutterTask flutter_task,
+                uint64_t flutter_target_time_nanos) override;
+
+ private:
+  using TaskTimePoint = std::chrono::steady_clock::time_point;
+  DWORD main_thread_id_;
+  TaskExpiredCallback on_task_expired_;
+
+  WinrtTaskRunner(const WinrtTaskRunner&) = delete;
+
+  WinrtTaskRunner& operator=(const WinrtTaskRunner&) = delete;
+
+  winrt::Windows::UI::Core::CoreDispatcher dispatcher_{nullptr};
+
+  static TaskTimePoint TimePointFromFlutterTime(
+      uint64_t flutter_target_time_nanos);
+};
+
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_WINRT_TASK_RUNNER_H_

From 287029c8a1364b2de53e5060655827859e708795 Mon Sep 17 00:00:00 2001
From: Stuart Morgan <stuartmorgan@google.com>
Date: Thu, 19 Nov 2020 11:18:30 -0800
Subject: [PATCH 08/19] Rename task runners

---
 ci/licenses_golden/licenses_flutter              |  8 ++++----
 shell/platform/windows/BUILD.gn                  |  8 ++++----
 shell/platform/windows/flutter_windows_engine.cc | 12 +++++++++---
 shell/platform/windows/flutter_windows_engine.h  |  3 ---
 shell/platform/windows/flutter_windows_win32.cc  |  2 +-
 ...win32_task_runner.cc => task_runner_win32.cc} | 14 +++++++-------
 .../{win32_task_runner.h => task_runner_win32.h} | 16 ++++++++--------
 ...inrt_task_runner.cc => task_runner_winuwp.cc} | 16 ++++++++--------
 ...{winrt_task_runner.h => task_runner_winuwp.h} | 12 ++++++------
 9 files changed, 47 insertions(+), 44 deletions(-)
 rename shell/platform/windows/{win32_task_runner.cc => task_runner_win32.cc} (88%)
 rename shell/platform/windows/{win32_task_runner.h => task_runner_win32.h} (83%)
 rename shell/platform/windows/{winrt_task_runner.cc => task_runner_winuwp.cc} (63%)
 rename shell/platform/windows/{winrt_task_runner.h => task_runner_winuwp.h} (78%)

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index 8ea36b71304ef..151875d9ecc8b 100755
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -1418,6 +1418,10 @@ FILE: ../../../flutter/shell/platform/windows/system_utils_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/system_utils_win32.cc
 FILE: ../../../flutter/shell/platform/windows/system_utils_winuwp.cc
 FILE: ../../../flutter/shell/platform/windows/task_runner.h
+FILE: ../../../flutter/shell/platform/windows/task_runner_win32.cc
+FILE: ../../../flutter/shell/platform/windows/task_runner_win32.h
+FILE: ../../../flutter/shell/platform/windows/task_runner_winuwp.cc
+FILE: ../../../flutter/shell/platform/windows/task_runner_winuwp.h
 FILE: ../../../flutter/shell/platform/windows/text_input_plugin.cc
 FILE: ../../../flutter/shell/platform/windows/text_input_plugin.h
 FILE: ../../../flutter/shell/platform/windows/win32_dpi_utils.cc
@@ -1428,8 +1432,6 @@ FILE: ../../../flutter/shell/platform/windows/win32_flutter_window.h
 FILE: ../../../flutter/shell/platform/windows/win32_flutter_window_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/win32_platform_handler.cc
 FILE: ../../../flutter/shell/platform/windows/win32_platform_handler.h
-FILE: ../../../flutter/shell/platform/windows/win32_task_runner.cc
-FILE: ../../../flutter/shell/platform/windows/win32_task_runner.h
 FILE: ../../../flutter/shell/platform/windows/win32_window.cc
 FILE: ../../../flutter/shell/platform/windows/win32_window.h
 FILE: ../../../flutter/shell/platform/windows/win32_window_proc_delegate_manager.cc
@@ -1439,8 +1441,6 @@ FILE: ../../../flutter/shell/platform/windows/win32_window_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/window_binding_handler.h
 FILE: ../../../flutter/shell/platform/windows/window_binding_handler_delegate.h
 FILE: ../../../flutter/shell/platform/windows/window_state.h
-FILE: ../../../flutter/shell/platform/windows/winrt_task_runner.cc
-FILE: ../../../flutter/shell/platform/windows/winrt_task_runner.h
 FILE: ../../../flutter/shell/profiling/sampling_profiler.cc
 FILE: ../../../flutter/shell/profiling/sampling_profiler.h
 FILE: ../../../flutter/shell/version/version.cc
diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index 9b39d66571213..98c6f70294cb1 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -74,21 +74,21 @@ source_set("flutter_windows_source") {
     sources += [
       "flutter_windows_winuwp.cc",
       "system_utils_winuwp.cc",
-      "winrt_task_runner.cc",
-      "winrt_task_runner.h",
+      "task_runner_winuwp.cc",
+      "task_runner_winuwp.h",
     ]
   } else {
     sources += [
       "flutter_windows_win32.cc",
       "system_utils_win32.cc",
+      "task_runner_win32.cc",
+      "task_runner_win32.h",
       "win32_dpi_utils.cc",
       "win32_dpi_utils.h",
       "win32_flutter_window.cc",
       "win32_flutter_window.h",
       "win32_platform_handler.cc",
       "win32_platform_handler.h",
-      "win32_task_runner.cc",
-      "win32_task_runner.h",
       "win32_window.cc",
       "win32_window.h",
       "win32_window_proc_delegate_manager.cc",
diff --git a/shell/platform/windows/flutter_windows_engine.cc b/shell/platform/windows/flutter_windows_engine.cc
index 0ce3c6d228094..2a53d94a0c3a2 100644
--- a/shell/platform/windows/flutter_windows_engine.cc
+++ b/shell/platform/windows/flutter_windows_engine.cc
@@ -14,6 +14,12 @@
 #include "flutter/shell/platform/windows/system_utils.h"
 #include "flutter/shell/platform/windows/task_runner.h"
 
+#ifdef WINUWP
+#include "flutter/shell/platform/windows/task_runner_winuwp.h"  // nogncheck
+#else
+#include "flutter/shell/platform/windows/task_runner_win32.h"  // nogncheck
+#endif
+
 namespace flutter {
 
 namespace {
@@ -95,9 +101,9 @@ FlutterWindowsEngine::FlutterWindowsEngine(const FlutterProjectBundle& project)
       aot_data_(nullptr, nullptr) {
   embedder_api_.struct_size = sizeof(FlutterEngineProcTable);
   FlutterEngineGetProcAddresses(&embedder_api_);
-  
+
 #ifndef WINUWP
-  task_runner_ = std::make_unique<Win32TaskRunner>(
+  task_runner_ = std::make_unique<TaskRunnerWin32>(
       GetCurrentThreadId(), embedder_api_.GetCurrentTime,
       [this](const auto* task) {
         if (!engine_) {
@@ -110,7 +116,7 @@ FlutterWindowsEngine::FlutterWindowsEngine(const FlutterProjectBundle& project)
         }
       });
 #else
-  task_runner_ = std::make_unique<WinrtTaskRunner>(
+  task_runner_ = std::make_unique<TaskRunnerWinUwp>(
       GetCurrentThreadId(), [this](const auto* task) {
         if (!engine_) {
           std::cerr << "Cannot post an engine task when engine is not running."
diff --git a/shell/platform/windows/flutter_windows_engine.h b/shell/platform/windows/flutter_windows_engine.h
index 873c1cd353327..0645389a8fc02 100644
--- a/shell/platform/windows/flutter_windows_engine.h
+++ b/shell/platform/windows/flutter_windows_engine.h
@@ -18,10 +18,7 @@
 #include "flutter/shell/platform/windows/window_state.h"
 
 #ifndef WINUWP
-#include "flutter/shell/platform/windows/win32_task_runner.h"  // nogncheck
 #include "flutter/shell/platform/windows/win32_window_proc_delegate_manager.h"  // nogncheck
-#else
-#include "flutter/shell/platform/windows/winrt_task_runner.h"  // nogncheck
 #endif
 
 namespace flutter {
diff --git a/shell/platform/windows/flutter_windows_win32.cc b/shell/platform/windows/flutter_windows_win32.cc
index 45dcf818413b7..3ebe73af2f654 100644
--- a/shell/platform/windows/flutter_windows_win32.cc
+++ b/shell/platform/windows/flutter_windows_win32.cc
@@ -15,9 +15,9 @@
 #include <memory>
 #include <vector>
 
+#include "flutter/shell/platform/windows/task_runner_win32.h"
 #include "flutter/shell/platform/windows/win32_dpi_utils.h"
 #include "flutter/shell/platform/windows/win32_flutter_window.h"
-#include "flutter/shell/platform/windows/win32_task_runner.h"
 
 // Returns the engine corresponding to the given opaque API handle.
 static flutter::FlutterWindowsEngine* EngineFromHandle(
diff --git a/shell/platform/windows/win32_task_runner.cc b/shell/platform/windows/task_runner_win32.cc
similarity index 88%
rename from shell/platform/windows/win32_task_runner.cc
rename to shell/platform/windows/task_runner_win32.cc
index 9f6d26db86b91..3eba0de83eaff 100644
--- a/shell/platform/windows/win32_task_runner.cc
+++ b/shell/platform/windows/task_runner_win32.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "flutter/shell/platform/windows/win32_task_runner.h"
+#include "flutter/shell/platform/windows/task_runner_win32.h"
 
 #include <atomic>
 #include <iostream>
@@ -10,20 +10,20 @@
 
 namespace flutter {
 
-Win32TaskRunner::Win32TaskRunner(DWORD main_thread_id,
+TaskRunnerWin32::TaskRunnerWin32(DWORD main_thread_id,
                                  CurrentTimeProc get_current_time,
                                  const TaskExpiredCallback& on_task_expired)
     : main_thread_id_(main_thread_id),
       get_current_time_(get_current_time),
       on_task_expired_(std::move(on_task_expired)) {}
 
-Win32TaskRunner::~Win32TaskRunner() = default;
+TaskRunnerWin32::~TaskRunnerWin32() = default;
 
-bool Win32TaskRunner::RunsTasksOnCurrentThread() const {
+bool TaskRunnerWin32::RunsTasksOnCurrentThread() const {
   return GetCurrentThreadId() == main_thread_id_;
 }
 
-std::chrono::nanoseconds Win32TaskRunner::ProcessTasks() {
+std::chrono::nanoseconds TaskRunnerWin32::ProcessTasks() {
   const TaskTimePoint now = TaskTimePoint::clock::now();
 
   std::vector<FlutterTask> expired_tasks;
@@ -68,14 +68,14 @@ std::chrono::nanoseconds Win32TaskRunner::ProcessTasks() {
   }
 }
 
-Win32TaskRunner::TaskTimePoint Win32TaskRunner::TimePointFromFlutterTime(
+TaskRunnerWin32::TaskTimePoint TaskRunnerWin32::TimePointFromFlutterTime(
     uint64_t flutter_target_time_nanos) const {
   const auto now = TaskTimePoint::clock::now();
   const auto flutter_duration = flutter_target_time_nanos - get_current_time_();
   return now + std::chrono::nanoseconds(flutter_duration);
 }
 
-void Win32TaskRunner::PostTask(FlutterTask flutter_task,
+void TaskRunnerWin32::PostTask(FlutterTask flutter_task,
                                uint64_t flutter_target_time_nanos) {
   static std::atomic_uint64_t sGlobalTaskOrder(0);
 
diff --git a/shell/platform/windows/win32_task_runner.h b/shell/platform/windows/task_runner_win32.h
similarity index 83%
rename from shell/platform/windows/win32_task_runner.h
rename to shell/platform/windows/task_runner_win32.h
index 8c9a17f53309c..126ab6e420343 100644
--- a/shell/platform/windows/win32_task_runner.h
+++ b/shell/platform/windows/task_runner_win32.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_WIN32_TASK_RUNNER_H_
-#define FLUTTER_SHELL_PLATFORM_WINDOWS_WIN32_TASK_RUNNER_H_
+#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_TASK_RUNNER_WIN32_H_
+#define FLUTTER_SHELL_PLATFORM_WINDOWS_TASK_RUNNER_WIN32_H_
 
 #include <windows.h>
 
@@ -23,16 +23,16 @@ typedef uint64_t (*CurrentTimeProc)();
 // A custom task runner that integrates with user32 GetMessage semantics so that
 // host app can own its own message loop and flutter still gets to process
 // tasks on a timely basis.
-class Win32TaskRunner : public TaskRunner {
+class TaskRunnerWin32 : public TaskRunner {
  public:
   using TaskExpiredCallback = std::function<void(const FlutterTask*)>;
   // Creates a new task runner with the given main thread ID, current time
   // provider, and callback for tasks that are ready to be run.
-  Win32TaskRunner(DWORD main_thread_id,
+  TaskRunnerWin32(DWORD main_thread_id,
                   CurrentTimeProc get_current_time,
                   const TaskExpiredCallback& on_task_expired);
 
-  virtual ~Win32TaskRunner();
+  virtual ~TaskRunnerWin32();
 
   // |RunsTasksOnCurrentThread|
   bool RunsTasksOnCurrentThread() const override;
@@ -70,11 +70,11 @@ class Win32TaskRunner : public TaskRunner {
   std::mutex task_queue_mutex_;
   std::priority_queue<Task, std::deque<Task>, Task::Comparer> task_queue_;
 
-  Win32TaskRunner(const Win32TaskRunner&) = delete;
+  TaskRunnerWin32(const TaskRunnerWin32&) = delete;
 
-  Win32TaskRunner& operator=(const Win32TaskRunner&) = delete;
+  TaskRunnerWin32& operator=(const TaskRunnerWin32&) = delete;
 };
 
 }  // namespace flutter
 
-#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_WIN32_TASK_RUNNER_H_
+#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_TASK_RUNNER_WIN32_H_
diff --git a/shell/platform/windows/winrt_task_runner.cc b/shell/platform/windows/task_runner_winuwp.cc
similarity index 63%
rename from shell/platform/windows/winrt_task_runner.cc
rename to shell/platform/windows/task_runner_winuwp.cc
index 56374a57cf5a7..781fd81ee882b 100644
--- a/shell/platform/windows/winrt_task_runner.cc
+++ b/shell/platform/windows/task_runner_winuwp.cc
@@ -2,28 +2,28 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "flutter/shell/platform/windows/winrt_task_runner.h"
+#include "flutter/shell/platform/windows/task_runner_winuwp.h"
 
 #include <atomic>
 #include <utility>
 
 namespace flutter {
 
-WinrtTaskRunner::WinrtTaskRunner(DWORD main_thread_id,
-                                 const TaskExpiredCallback& on_task_expired)
+TaskRunnerWinUwp::TaskRunnerWinUwp(DWORD main_thread_id,
+                                   const TaskExpiredCallback& on_task_expired)
     : main_thread_id_(main_thread_id),
       on_task_expired_(std::move(on_task_expired)) {
   dispatcher_ =
       winrt::Windows::UI::Core::CoreWindow::GetForCurrentThread().Dispatcher();
 }
 
-WinrtTaskRunner::~WinrtTaskRunner() = default;
+TaskRunnerWinUwp::~TaskRunnerWinUwp() = default;
 
-bool WinrtTaskRunner::RunsTasksOnCurrentThread() const {
+bool TaskRunnerWinUwp::RunsTasksOnCurrentThread() const {
   return GetCurrentThreadId() == main_thread_id_;
 }
 
-WinrtTaskRunner::TaskTimePoint WinrtTaskRunner::TimePointFromFlutterTime(
+TaskRunnerWinUwp::TaskTimePoint TaskRunnerWinUwp::TimePointFromFlutterTime(
     uint64_t flutter_target_time_nanos) {
   const auto now = TaskTimePoint::clock::now();
   const auto flutter_duration =
@@ -31,8 +31,8 @@ WinrtTaskRunner::TaskTimePoint WinrtTaskRunner::TimePointFromFlutterTime(
   return now + std::chrono::nanoseconds(flutter_duration);
 }
 
-void WinrtTaskRunner::PostTask(FlutterTask flutter_task,
-                               uint64_t flutter_target_time_nanos) {
+void TaskRunnerWinUwp::PostTask(FlutterTask flutter_task,
+                                uint64_t flutter_target_time_nanos) {
   // TODO: consider waiting on threadpool thread until target time
 
   dispatcher_.RunAsync(
diff --git a/shell/platform/windows/winrt_task_runner.h b/shell/platform/windows/task_runner_winuwp.h
similarity index 78%
rename from shell/platform/windows/winrt_task_runner.h
rename to shell/platform/windows/task_runner_winuwp.h
index 79ee79c26d454..0e2e0b2e88bf0 100644
--- a/shell/platform/windows/winrt_task_runner.h
+++ b/shell/platform/windows/task_runner_winuwp.h
@@ -20,13 +20,13 @@ namespace flutter {
 
 // A custom task runner that uses a CoreDispatcher to schedule
 // flutter tasks.
-class WinrtTaskRunner : public TaskRunner {
+class TaskRunnerWinUwp : public TaskRunner {
  public:
   using TaskExpiredCallback = std::function<void(const FlutterTask*)>;
-  WinrtTaskRunner(DWORD main_thread_id,
-                  const TaskExpiredCallback& on_task_expired);
+  TaskRunnerWinUwp(DWORD main_thread_id,
+                   const TaskExpiredCallback& on_task_expired);
 
-  ~WinrtTaskRunner();
+  ~TaskRunnerWinUwp();
 
   // |RunsTasksOnCurrentThread|
   bool RunsTasksOnCurrentThread() const override;
@@ -40,9 +40,9 @@ class WinrtTaskRunner : public TaskRunner {
   DWORD main_thread_id_;
   TaskExpiredCallback on_task_expired_;
 
-  WinrtTaskRunner(const WinrtTaskRunner&) = delete;
+  TaskRunnerWinUwp(const TaskRunnerWinUwp&) = delete;
 
-  WinrtTaskRunner& operator=(const WinrtTaskRunner&) = delete;
+  TaskRunnerWinUwp& operator=(const TaskRunnerWinUwp&) = delete;
 
   winrt::Windows::UI::Core::CoreDispatcher dispatcher_{nullptr};
 

From fd8b6907deacaad0fbeaceb88bd62638df1e706a Mon Sep 17 00:00:00 2001
From: Stuart Morgan <stuartmorgan@google.com>
Date: Thu, 19 Nov 2020 14:52:18 -0800
Subject: [PATCH 09/19] Minor cleanup

---
 BUILD.gn                                      |  4 ++--
 shell/platform/windows/flutter_windows_view.h |  7 ++++---
 shell/platform/windows/task_runner_win32.h    |  8 ++++----
 shell/platform/windows/task_runner_winuwp.cc  | 11 ++---------
 shell/platform/windows/task_runner_winuwp.h   | 15 +++++----------
 tools/gn                                      |  2 --
 6 files changed, 17 insertions(+), 30 deletions(-)

diff --git a/BUILD.gn b/BUILD.gn
index 73e525a4babca..a4f3247f15211 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -148,8 +148,8 @@ group("flutter") {
 
       if (is_win) {
         if (target_os == "winuwp") {
-          # TODO once the UWP implmentation lands, reference future flutter_windows_unittests_winrt
-          # runner implementation from here.
+          # TODO: Add winnup variant of the unit tests here; see
+          # https://github.com/flutter/flutter/issues/70197
         } else {
           public_deps += [
             "//flutter/shell/platform/windows:flutter_windows_unittests",
diff --git a/shell/platform/windows/flutter_windows_view.h b/shell/platform/windows/flutter_windows_view.h
index 462a2285d0879..25cc9b8b1f3ce 100644
--- a/shell/platform/windows/flutter_windows_view.h
+++ b/shell/platform/windows/flutter_windows_view.h
@@ -20,13 +20,14 @@
 #include "flutter/shell/platform/windows/keyboard_hook_handler.h"
 #include "flutter/shell/platform/windows/public/flutter_windows.h"
 #include "flutter/shell/platform/windows/text_input_plugin.h"
-#ifndef WINUWP
-#include "flutter/shell/platform/windows/win32_platform_handler.h"  // nogncheck
-#endif
 #include "flutter/shell/platform/windows/window_binding_handler.h"
 #include "flutter/shell/platform/windows/window_binding_handler_delegate.h"
 #include "flutter/shell/platform/windows/window_state.h"
 
+#ifndef WINUWP
+#include "flutter/shell/platform/windows/win32_platform_handler.h"  // nogncheck
+#endif
+
 namespace flutter {
 
 // An OS-windowing neutral abstration for flutter
diff --git a/shell/platform/windows/task_runner_win32.h b/shell/platform/windows/task_runner_win32.h
index 126ab6e420343..aa73cd998d134 100644
--- a/shell/platform/windows/task_runner_win32.h
+++ b/shell/platform/windows/task_runner_win32.h
@@ -34,15 +34,15 @@ class TaskRunnerWin32 : public TaskRunner {
 
   virtual ~TaskRunnerWin32();
 
-  // |RunsTasksOnCurrentThread|
+  // |TaskRunner|
   bool RunsTasksOnCurrentThread() const override;
 
-  std::chrono::nanoseconds ProcessTasks();
-
-  // |PostTask|
+  // |TaskRunner|
   void PostTask(FlutterTask flutter_task,
                 uint64_t flutter_target_time_nanos) override;
 
+  std::chrono::nanoseconds ProcessTasks();
+
  private:
   using TaskTimePoint = std::chrono::steady_clock::time_point;
   struct Task {
diff --git a/shell/platform/windows/task_runner_winuwp.cc b/shell/platform/windows/task_runner_winuwp.cc
index 781fd81ee882b..863cb5eadfdbd 100644
--- a/shell/platform/windows/task_runner_winuwp.cc
+++ b/shell/platform/windows/task_runner_winuwp.cc
@@ -23,17 +23,10 @@ bool TaskRunnerWinUwp::RunsTasksOnCurrentThread() const {
   return GetCurrentThreadId() == main_thread_id_;
 }
 
-TaskRunnerWinUwp::TaskTimePoint TaskRunnerWinUwp::TimePointFromFlutterTime(
-    uint64_t flutter_target_time_nanos) {
-  const auto now = TaskTimePoint::clock::now();
-  const auto flutter_duration =
-      flutter_target_time_nanos - FlutterEngineGetCurrentTime();
-  return now + std::chrono::nanoseconds(flutter_duration);
-}
-
 void TaskRunnerWinUwp::PostTask(FlutterTask flutter_task,
                                 uint64_t flutter_target_time_nanos) {
-  // TODO: consider waiting on threadpool thread until target time
+  // TODO: Handle the target time. See
+  // https://github.com/flutter/flutter/issues/70890.
 
   dispatcher_.RunAsync(
       winrt::Windows::UI::Core::CoreDispatcherPriority::Normal,
diff --git a/shell/platform/windows/task_runner_winuwp.h b/shell/platform/windows/task_runner_winuwp.h
index 0e2e0b2e88bf0..69364dca025c4 100644
--- a/shell/platform/windows/task_runner_winuwp.h
+++ b/shell/platform/windows/task_runner_winuwp.h
@@ -28,26 +28,21 @@ class TaskRunnerWinUwp : public TaskRunner {
 
   ~TaskRunnerWinUwp();
 
-  // |RunsTasksOnCurrentThread|
+  TaskRunnerWinUwp(const TaskRunnerWinUwp&) = delete;
+  TaskRunnerWinUwp& operator=(const TaskRunnerWinUwp&) = delete;
+
+  // |TaskRunner|
   bool RunsTasksOnCurrentThread() const override;
 
-  // |PostTask|
+  // |TaskRunner|
   void PostTask(FlutterTask flutter_task,
                 uint64_t flutter_target_time_nanos) override;
 
  private:
-  using TaskTimePoint = std::chrono::steady_clock::time_point;
   DWORD main_thread_id_;
   TaskExpiredCallback on_task_expired_;
 
-  TaskRunnerWinUwp(const TaskRunnerWinUwp&) = delete;
-
-  TaskRunnerWinUwp& operator=(const TaskRunnerWinUwp&) = delete;
-
   winrt::Windows::UI::Core::CoreDispatcher dispatcher_{nullptr};
-
-  static TaskTimePoint TimePointFromFlutterTime(
-      uint64_t flutter_target_time_nanos);
 };
 
 }  // namespace flutter
diff --git a/tools/gn b/tools/gn
index e7ac66ac416fa..1548795331a5f 100755
--- a/tools/gn
+++ b/tools/gn
@@ -141,8 +141,6 @@ def to_gn_args(args):
         gn_args['flutter_enable_legacy_fuchsia_embedder'] = args.fuchsia_legacy
     elif args.target_os == 'winuwp':
         gn_args['target_os'] = 'winuwp'
-        # Enabling angle_is_winuwp is dependent on an in-flight patch to https://chromium.googlesource.com/angle/angle to update UWP support
-        # gn_args['angle_is_winuwp'] = True
     elif args.target_os is not None:
         gn_args['target_os'] = args.target_os
 

From b6fa93813c13062980a47633daa9b10cfb61b14e Mon Sep 17 00:00:00 2001
From: Stuart Morgan <stuartmorgan@google.com>
Date: Thu, 19 Nov 2020 15:09:54 -0800
Subject: [PATCH 10/19] TaskRunner factory

---
 .../windows/flutter_windows_engine.cc         | 22 +------------------
 shell/platform/windows/task_runner.h          | 11 ++++++++++
 shell/platform/windows/task_runner_win32.cc   |  9 ++++++++
 shell/platform/windows/task_runner_win32.h    |  2 --
 shell/platform/windows/task_runner_winuwp.cc  |  8 +++++++
 shell/platform/windows/task_runner_winuwp.h   |  1 -
 6 files changed, 29 insertions(+), 24 deletions(-)

diff --git a/shell/platform/windows/flutter_windows_engine.cc b/shell/platform/windows/flutter_windows_engine.cc
index 2a53d94a0c3a2..24e65e31ec054 100644
--- a/shell/platform/windows/flutter_windows_engine.cc
+++ b/shell/platform/windows/flutter_windows_engine.cc
@@ -14,12 +14,6 @@
 #include "flutter/shell/platform/windows/system_utils.h"
 #include "flutter/shell/platform/windows/task_runner.h"
 
-#ifdef WINUWP
-#include "flutter/shell/platform/windows/task_runner_winuwp.h"  // nogncheck
-#else
-#include "flutter/shell/platform/windows/task_runner_win32.h"  // nogncheck
-#endif
-
 namespace flutter {
 
 namespace {
@@ -102,8 +96,7 @@ FlutterWindowsEngine::FlutterWindowsEngine(const FlutterProjectBundle& project)
   embedder_api_.struct_size = sizeof(FlutterEngineProcTable);
   FlutterEngineGetProcAddresses(&embedder_api_);
 
-#ifndef WINUWP
-  task_runner_ = std::make_unique<TaskRunnerWin32>(
+  task_runner_ = TaskRunner::Create(
       GetCurrentThreadId(), embedder_api_.GetCurrentTime,
       [this](const auto* task) {
         if (!engine_) {
@@ -115,19 +108,6 @@ FlutterWindowsEngine::FlutterWindowsEngine(const FlutterProjectBundle& project)
           std::cerr << "Failed to post an engine task." << std::endl;
         }
       });
-#else
-  task_runner_ = std::make_unique<TaskRunnerWinUwp>(
-      GetCurrentThreadId(), [this](const auto* task) {
-        if (!engine_) {
-          std::cerr << "Cannot post an engine task when engine is not running."
-                    << std::endl;
-          return;
-        }
-        if (FlutterEngineRunTask(engine_, task) != kSuccess) {
-          std::cerr << "Failed to post an engine task." << std::endl;
-        }
-      });
-#endif
 
   // Set up the legacy structs backing the API handles.
   messenger_ = std::make_unique<FlutterDesktopMessenger>();
diff --git a/shell/platform/windows/task_runner.h b/shell/platform/windows/task_runner.h
index 61f33f2361d38..9d2c22b9043c0 100644
--- a/shell/platform/windows/task_runner.h
+++ b/shell/platform/windows/task_runner.h
@@ -14,9 +14,13 @@
 
 namespace flutter {
 
+typedef uint64_t (*CurrentTimeProc)();
+
 // Abstract custom task runner for scheduling custom tasks.
 class TaskRunner {
  public:
+  using TaskExpiredCallback = std::function<void(const FlutterTask*)>;
+
   virtual ~TaskRunner() = default;
 
   // Returns if the current thread is the UI thread.
@@ -25,6 +29,13 @@ class TaskRunner {
   // Post a Flutter engine tasks to the event loop for delayed execution.
   virtual void PostTask(FlutterTask flutter_task,
                         uint64_t flutter_target_time_nanos) = 0;
+
+  // Creates a new task runner with the given main thread ID, current time
+  // provider, and callback for tasks that are ready to be run.
+  static std::unique_ptr<TaskRunner> Create(
+      DWORD main_thread_id,
+      CurrentTimeProc get_current_time,
+      const TaskExpiredCallback& on_task_expired);
 };
 
 }  // namespace flutter
diff --git a/shell/platform/windows/task_runner_win32.cc b/shell/platform/windows/task_runner_win32.cc
index 3eba0de83eaff..bb1fe147707de 100644
--- a/shell/platform/windows/task_runner_win32.cc
+++ b/shell/platform/windows/task_runner_win32.cc
@@ -10,6 +10,15 @@
 
 namespace flutter {
 
+// static
+std::unique_ptr<TaskRunner> TaskRunner::Create(
+    DWORD main_thread_id,
+    CurrentTimeProc get_current_time,
+    const TaskExpiredCallback& on_task_expired) {
+  return std::make_unique<TaskRunnerWin32>(main_thread_id, get_current_time,
+                                           on_task_expired);
+}
+
 TaskRunnerWin32::TaskRunnerWin32(DWORD main_thread_id,
                                  CurrentTimeProc get_current_time,
                                  const TaskExpiredCallback& on_task_expired)
diff --git a/shell/platform/windows/task_runner_win32.h b/shell/platform/windows/task_runner_win32.h
index aa73cd998d134..1ac2f64b861c5 100644
--- a/shell/platform/windows/task_runner_win32.h
+++ b/shell/platform/windows/task_runner_win32.h
@@ -19,13 +19,11 @@
 
 namespace flutter {
 
-typedef uint64_t (*CurrentTimeProc)();
 // A custom task runner that integrates with user32 GetMessage semantics so that
 // host app can own its own message loop and flutter still gets to process
 // tasks on a timely basis.
 class TaskRunnerWin32 : public TaskRunner {
  public:
-  using TaskExpiredCallback = std::function<void(const FlutterTask*)>;
   // Creates a new task runner with the given main thread ID, current time
   // provider, and callback for tasks that are ready to be run.
   TaskRunnerWin32(DWORD main_thread_id,
diff --git a/shell/platform/windows/task_runner_winuwp.cc b/shell/platform/windows/task_runner_winuwp.cc
index 863cb5eadfdbd..a2fbe7040c412 100644
--- a/shell/platform/windows/task_runner_winuwp.cc
+++ b/shell/platform/windows/task_runner_winuwp.cc
@@ -9,6 +9,14 @@
 
 namespace flutter {
 
+// static
+std::unique_ptr<TaskRunner> TaskRunner::Create(
+    DWORD main_thread_id,
+    CurrentTimeProc get_current_time,
+    const TaskExpiredCallback& on_task_expired) {
+  return std::make_unique<TaskRunnerWinUwp>(main_thread_id, on_task_expired);
+}
+
 TaskRunnerWinUwp::TaskRunnerWinUwp(DWORD main_thread_id,
                                    const TaskExpiredCallback& on_task_expired)
     : main_thread_id_(main_thread_id),
diff --git a/shell/platform/windows/task_runner_winuwp.h b/shell/platform/windows/task_runner_winuwp.h
index 69364dca025c4..49bdb4da587ce 100644
--- a/shell/platform/windows/task_runner_winuwp.h
+++ b/shell/platform/windows/task_runner_winuwp.h
@@ -22,7 +22,6 @@ namespace flutter {
 // flutter tasks.
 class TaskRunnerWinUwp : public TaskRunner {
  public:
-  using TaskExpiredCallback = std::function<void(const FlutterTask*)>;
   TaskRunnerWinUwp(DWORD main_thread_id,
                    const TaskExpiredCallback& on_task_expired);
 

From 9576f5c547f4004d47b7ae801f4108608d25d7b2 Mon Sep 17 00:00:00 2001
From: Stuart Morgan <stuartmorgan@google.com>
Date: Mon, 23 Nov 2020 14:01:08 -0800
Subject: [PATCH 11/19] Abstract PlatformHandler. Minor fixes

---
 ci/licenses_golden/licenses_flutter           |   8 +-
 shell/platform/windows/BUILD.gn               |   8 +-
 .../platform/windows/flutter_windows_view.cc  |   5 +-
 shell/platform/windows/flutter_windows_view.h |   7 +-
 .../platform/windows/flutter_windows_win32.cc |   2 +-
 shell/platform/windows/platform_handler.cc    |  62 ++++++++
 shell/platform/windows/platform_handler.h     |  55 +++++++
 ...m_handler.cc => platform_handler_win32.cc} | 148 +++++++-----------
 .../platform/windows/platform_handler_win32.h |  43 +++++
 .../windows/platform_handler_winuwp.cc        |  38 +++++
 .../windows/platform_handler_winuwp.h         |  43 +++++
 .../platform/windows/win32_platform_handler.h |  38 -----
 12 files changed, 313 insertions(+), 144 deletions(-)
 create mode 100644 shell/platform/windows/platform_handler.cc
 create mode 100644 shell/platform/windows/platform_handler.h
 rename shell/platform/windows/{win32_platform_handler.cc => platform_handler_win32.cc} (57%)
 create mode 100644 shell/platform/windows/platform_handler_win32.h
 create mode 100644 shell/platform/windows/platform_handler_winuwp.cc
 create mode 100644 shell/platform/windows/platform_handler_winuwp.h
 delete mode 100644 shell/platform/windows/win32_platform_handler.h

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index 151875d9ecc8b..c7018129e1381 100755
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -1409,6 +1409,12 @@ FILE: ../../../flutter/shell/platform/windows/flutter_windows_view.h
 FILE: ../../../flutter/shell/platform/windows/key_event_handler.cc
 FILE: ../../../flutter/shell/platform/windows/key_event_handler.h
 FILE: ../../../flutter/shell/platform/windows/keyboard_hook_handler.h
+FILE: ../../../flutter/shell/platform/windows/platform_handler.cc
+FILE: ../../../flutter/shell/platform/windows/platform_handler.h
+FILE: ../../../flutter/shell/platform/windows/platform_handler_win32.cc
+FILE: ../../../flutter/shell/platform/windows/platform_handler_win32.h
+FILE: ../../../flutter/shell/platform/windows/platform_handler_winuwp.cc
+FILE: ../../../flutter/shell/platform/windows/platform_handler_winuwp.h
 FILE: ../../../flutter/shell/platform/windows/public/flutter_windows.h
 FILE: ../../../flutter/shell/platform/windows/string_conversion.cc
 FILE: ../../../flutter/shell/platform/windows/string_conversion.h
@@ -1430,8 +1436,6 @@ FILE: ../../../flutter/shell/platform/windows/win32_dpi_utils_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/win32_flutter_window.cc
 FILE: ../../../flutter/shell/platform/windows/win32_flutter_window.h
 FILE: ../../../flutter/shell/platform/windows/win32_flutter_window_unittests.cc
-FILE: ../../../flutter/shell/platform/windows/win32_platform_handler.cc
-FILE: ../../../flutter/shell/platform/windows/win32_platform_handler.h
 FILE: ../../../flutter/shell/platform/windows/win32_window.cc
 FILE: ../../../flutter/shell/platform/windows/win32_window.h
 FILE: ../../../flutter/shell/platform/windows/win32_window_proc_delegate_manager.cc
diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index 98c6f70294cb1..86794d4d1b01e 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -58,6 +58,8 @@ source_set("flutter_windows_source") {
     "key_event_handler.cc",
     "key_event_handler.h",
     "keyboard_hook_handler.h",
+    "platform_handler.cc",
+    "platform_handler.h",
     "string_conversion.cc",
     "string_conversion.h",
     "system_utils.h",
@@ -73,6 +75,8 @@ source_set("flutter_windows_source") {
   if (target_os == "winuwp") {
     sources += [
       "flutter_windows_winuwp.cc",
+      "platform_handler_winuwp.cc",
+      "platform_handler_winuwp.h",
       "system_utils_winuwp.cc",
       "task_runner_winuwp.cc",
       "task_runner_winuwp.h",
@@ -80,6 +84,8 @@ source_set("flutter_windows_source") {
   } else {
     sources += [
       "flutter_windows_win32.cc",
+      "platform_handler_win32.cc",
+      "platform_handler_win32.h",
       "system_utils_win32.cc",
       "task_runner_win32.cc",
       "task_runner_win32.h",
@@ -87,8 +93,6 @@ source_set("flutter_windows_source") {
       "win32_dpi_utils.h",
       "win32_flutter_window.cc",
       "win32_flutter_window.h",
-      "win32_platform_handler.cc",
-      "win32_platform_handler.h",
       "win32_window.cc",
       "win32_window.h",
       "win32_window_proc_delegate_manager.cc",
diff --git a/shell/platform/windows/flutter_windows_view.cc b/shell/platform/windows/flutter_windows_view.cc
index 0c2a568d96c56..bcac661aa17fb 100644
--- a/shell/platform/windows/flutter_windows_view.cc
+++ b/shell/platform/windows/flutter_windows_view.cc
@@ -39,10 +39,7 @@ void FlutterWindowsView::SetEngine(
       std::make_unique<flutter::KeyEventHandler>(internal_plugin_messenger));
   keyboard_hook_handlers_.push_back(
       std::make_unique<flutter::TextInputPlugin>(internal_plugin_messenger));
-#ifndef WINUWP
-  platform_handler_ = std::make_unique<flutter::PlatformHandler>(
-      internal_plugin_messenger, this);
-#endif
+  platform_handler_ = PlatformHandler::Create(internal_plugin_messenger, this);
   cursor_handler_ = std::make_unique<flutter::CursorHandler>(
       internal_plugin_messenger, binding_handler_.get());
 
diff --git a/shell/platform/windows/flutter_windows_view.h b/shell/platform/windows/flutter_windows_view.h
index 25cc9b8b1f3ce..4863ef7b1a30f 100644
--- a/shell/platform/windows/flutter_windows_view.h
+++ b/shell/platform/windows/flutter_windows_view.h
@@ -18,16 +18,13 @@
 #include "flutter/shell/platform/windows/flutter_windows_engine.h"
 #include "flutter/shell/platform/windows/key_event_handler.h"
 #include "flutter/shell/platform/windows/keyboard_hook_handler.h"
+#include "flutter/shell/platform/windows/platform_handler.h"
 #include "flutter/shell/platform/windows/public/flutter_windows.h"
 #include "flutter/shell/platform/windows/text_input_plugin.h"
 #include "flutter/shell/platform/windows/window_binding_handler.h"
 #include "flutter/shell/platform/windows/window_binding_handler_delegate.h"
 #include "flutter/shell/platform/windows/window_state.h"
 
-#ifndef WINUWP
-#include "flutter/shell/platform/windows/win32_platform_handler.h"  // nogncheck
-#endif
-
 namespace flutter {
 
 // An OS-windowing neutral abstration for flutter
@@ -201,10 +198,8 @@ class FlutterWindowsView : public WindowBindingHandlerDelegate {
   std::vector<std::unique_ptr<flutter::KeyboardHookHandler>>
       keyboard_hook_handlers_;
 
-#ifndef WINUWP
   // Handler for the flutter/platform channel.
   std::unique_ptr<flutter::PlatformHandler> platform_handler_;
-#endif
 
   // Handler for cursor events.
   std::unique_ptr<flutter::CursorHandler> cursor_handler_;
diff --git a/shell/platform/windows/flutter_windows_win32.cc b/shell/platform/windows/flutter_windows_win32.cc
index 3ebe73af2f654..4ee427eac5144 100644
--- a/shell/platform/windows/flutter_windows_win32.cc
+++ b/shell/platform/windows/flutter_windows_win32.cc
@@ -69,7 +69,7 @@ bool FlutterDesktopViewControllerHandleTopLevelWindowProc(
 }
 
 uint64_t FlutterDesktopEngineProcessMessages(FlutterDesktopEngineRef engine) {
-  return static_cast<flutter::Win32TaskRunner*>(
+  return static_cast<flutter::TaskRunnerWin32*>(
              EngineFromHandle(engine)->task_runner())
       ->ProcessTasks()
       .count();
diff --git a/shell/platform/windows/platform_handler.cc b/shell/platform/windows/platform_handler.cc
new file mode 100644
index 0000000000000..6267583a80a7e
--- /dev/null
+++ b/shell/platform/windows/platform_handler.cc
@@ -0,0 +1,62 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/windows/platform_handler.h"
+
+#include "flutter/shell/platform/common/cpp/json_method_codec.h"
+
+static constexpr char kChannelName[] = "flutter/platform";
+
+static constexpr char kGetClipboardDataMethod[] = "Clipboard.getData";
+static constexpr char kSetClipboardDataMethod[] = "Clipboard.setData";
+
+static constexpr char kTextPlainFormat[] = "text/plain";
+static constexpr char kTextKey[] = "text";
+
+static constexpr char kUnknownClipboardFormatMessage[] =
+    "Unknown clipboard format";
+
+namespace flutter {
+
+PlatformHandler::PlatformHandler(BinaryMessenger* messenger)
+    : channel_(std::make_unique<MethodChannel<rapidjson::Document>>(
+          messenger,
+          kChannelName,
+          &JsonMethodCodec::GetInstance())) {
+  channel_->SetMethodCallHandler(
+      [this](const MethodCall<rapidjson::Document>& call,
+             std::unique_ptr<MethodResult<rapidjson::Document>> result) {
+        HandleMethodCall(call, std::move(result));
+      });
+}
+
+PlatformHandler::~PlatformHandler() = default;
+
+void PlatformHandler::HandleMethodCall(
+    const MethodCall<rapidjson::Document>& method_call,
+    std::unique_ptr<MethodResult<rapidjson::Document>> result) {
+  const std::string& method = method_call.method_name();
+  if (method.compare(kGetClipboardDataMethod) == 0) {
+    // Only one string argument is expected.
+    const rapidjson::Value& format = method_call.arguments()[0];
+
+    if (strcmp(format.GetString(), kTextPlainFormat) != 0) {
+      result->Error(kClipboardError, kUnknownClipboardFormatMessage);
+      return;
+    }
+    GetPlainText(std::move(result), kTextKey);
+  } else if (method.compare(kSetClipboardDataMethod) == 0) {
+    const rapidjson::Value& document = *method_call.arguments();
+    rapidjson::Value::ConstMemberIterator itr = document.FindMember(kTextKey);
+    if (itr == document.MemberEnd()) {
+      result->Error(kClipboardError, kUnknownClipboardFormatMessage);
+      return;
+    }
+    SetPlainText(itr->value.GetString(), std::move(result));
+  } else {
+    result->NotImplemented();
+  }
+}
+
+}  // namespace flutter
diff --git a/shell/platform/windows/platform_handler.h b/shell/platform/windows/platform_handler.h
new file mode 100644
index 0000000000000..ba5a86ea0d8ed
--- /dev/null
+++ b/shell/platform/windows/platform_handler.h
@@ -0,0 +1,55 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_H_
+#define FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_H_
+
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/binary_messenger.h"
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/method_channel.h"
+#include "rapidjson/document.h"
+
+namespace flutter {
+
+class FlutterWindowsView;
+
+// Handler for internal system channels.
+class PlatformHandler {
+ public:
+  explicit PlatformHandler(BinaryMessenger* messenger);
+
+  virtual ~PlatformHandler();
+
+  // Creates a new platform handler using the given messenger and view.
+  static std::unique_ptr<PlatformHandler> Create(BinaryMessenger* messenger,
+                                                 FlutterWindowsView* view);
+
+ protected:
+  // Gets plain text from the clipboard and provides it to |result| as the
+  // value in a dictionary with the given |key|.
+  virtual void GetPlainText(
+      std::unique_ptr<MethodResult<rapidjson::Document>> result,
+      const char* key) = 0;
+
+  // Sets the clipboard's plain text to |text|, and reports the result (either
+  // an error, or null for success) to |result|.
+  virtual void SetPlainText(
+      const std::string& text,
+      std::unique_ptr<MethodResult<rapidjson::Document>> result) = 0;
+
+  // A error type to use for error responses.
+  static constexpr char kClipboardError[] = "Clipboard error";
+
+ private:
+  // Called when a method is called on |channel_|;
+  void HandleMethodCall(
+      const MethodCall<rapidjson::Document>& method_call,
+      std::unique_ptr<MethodResult<rapidjson::Document>> result);
+
+  // The MethodChannel used for communication with the Flutter engine.
+  std::unique_ptr<MethodChannel<rapidjson::Document>> channel_;
+};
+
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_H_
diff --git a/shell/platform/windows/win32_platform_handler.cc b/shell/platform/windows/platform_handler_win32.cc
similarity index 57%
rename from shell/platform/windows/win32_platform_handler.cc
rename to shell/platform/windows/platform_handler_win32.cc
index 63543dfb8de16..f891bd540421a 100644
--- a/shell/platform/windows/win32_platform_handler.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "flutter/shell/platform/windows/win32_platform_handler.h"
+#include "flutter/shell/platform/windows/platform_handler_win32.h"
 
 #include <windows.h>
 
@@ -10,22 +10,9 @@
 #include <iostream>
 #include <optional>
 
-#include "flutter/shell/platform/common/cpp/json_method_codec.h"
 #include "flutter/shell/platform/windows/flutter_windows_view.h"
 #include "flutter/shell/platform/windows/string_conversion.h"
 
-static constexpr char kChannelName[] = "flutter/platform";
-
-static constexpr char kGetClipboardDataMethod[] = "Clipboard.getData";
-static constexpr char kSetClipboardDataMethod[] = "Clipboard.setData";
-
-static constexpr char kTextPlainFormat[] = "text/plain";
-static constexpr char kTextKey[] = "text";
-
-static constexpr char kClipboardError[] = "Clipboard error";
-static constexpr char kUnknownClipboardFormatMessage[] =
-    "Unknown clipboard format";
-
 namespace flutter {
 
 namespace {
@@ -198,88 +185,67 @@ bool ScopedClipboard::SetString(const std::wstring string) {
 
 }  // namespace
 
-PlatformHandler::PlatformHandler(flutter::BinaryMessenger* messenger,
-                                 FlutterWindowsView* view)
-    : channel_(std::make_unique<flutter::MethodChannel<rapidjson::Document>>(
-          messenger,
-          kChannelName,
-          &flutter::JsonMethodCodec::GetInstance())),
-      view_(view) {
-  channel_->SetMethodCallHandler(
-      [this](
-          const flutter::MethodCall<rapidjson::Document>& call,
-          std::unique_ptr<flutter::MethodResult<rapidjson::Document>> result) {
-        HandleMethodCall(call, std::move(result));
-      });
+// static
+std::unique_ptr<PlatformHandler> PlatformHandler::Create(
+    BinaryMessenger* messenger,
+    FlutterWindowsView* view) {
+  return std::make_unique<PlatformHandlerWin32>(messenger, view);
 }
 
-void PlatformHandler::HandleMethodCall(
-    const flutter::MethodCall<rapidjson::Document>& method_call,
-    std::unique_ptr<flutter::MethodResult<rapidjson::Document>> result) {
-  const std::string& method = method_call.method_name();
-  if (method.compare(kGetClipboardDataMethod) == 0) {
-    // Only one string argument is expected.
-    const rapidjson::Value& format = method_call.arguments()[0];
-
-    if (strcmp(format.GetString(), kTextPlainFormat) != 0) {
-      result->Error(kClipboardError, kUnknownClipboardFormatMessage);
-      return;
-    }
-    ScopedClipboard clipboard;
-    if (!clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()))) {
-      rapidjson::Document error_code;
-      error_code.SetInt(::GetLastError());
-      result->Error(kClipboardError, "Unable to open clipboard", error_code);
-      return;
-    }
-    if (!clipboard.HasString()) {
-      result->Success(rapidjson::Document());
-      return;
-    }
-    std::optional<std::wstring> clipboard_string = clipboard.GetString();
-    if (!clipboard_string) {
-      rapidjson::Document error_code;
-      error_code.SetInt(::GetLastError());
-      result->Error(kClipboardError, "Unable to get clipboard data",
-                    error_code);
-      return;
-    }
-
-    rapidjson::Document document;
-    document.SetObject();
-    rapidjson::Document::AllocatorType& allocator = document.GetAllocator();
-    document.AddMember(
-        rapidjson::Value(kTextKey, allocator),
-        rapidjson::Value(Utf8FromUtf16(*clipboard_string), allocator),
-        allocator);
-    result->Success(document);
-  } else if (method.compare(kSetClipboardDataMethod) == 0) {
-    const rapidjson::Value& document = *method_call.arguments();
-    rapidjson::Value::ConstMemberIterator itr = document.FindMember(kTextKey);
-    if (itr == document.MemberEnd()) {
-      result->Error(kClipboardError, kUnknownClipboardFormatMessage);
-      return;
-    }
+PlatformHandlerWin32::PlatformHandlerWin32(BinaryMessenger* messenger,
+                                           FlutterWindowsView* view)
+    : PlatformHandler(messenger), view_(view) {}
+
+PlatformHandlerWin32::~PlatformHandlerWin32() = default;
+
+void PlatformHandlerWin32::GetPlainText(
+    std::unique_ptr<MethodResult<rapidjson::Document>> result,
+    const char* key) {
+  ScopedClipboard clipboard;
+  if (!clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()))) {
+    rapidjson::Document error_code;
+    error_code.SetInt(::GetLastError());
+    result->Error(kClipboardError, "Unable to open clipboard", error_code);
+    return;
+  }
+  if (!clipboard.HasString()) {
+    result->Success(rapidjson::Document());
+    return;
+  }
+  std::optional<std::wstring> clipboard_string = clipboard.GetString();
+  if (!clipboard_string) {
+    rapidjson::Document error_code;
+    error_code.SetInt(::GetLastError());
+    result->Error(kClipboardError, "Unable to get clipboard data", error_code);
+    return;
+  }
 
-    ScopedClipboard clipboard;
+  rapidjson::Document document;
+  document.SetObject();
+  rapidjson::Document::AllocatorType& allocator = document.GetAllocator();
+  document.AddMember(
+      rapidjson::Value(key, allocator),
+      rapidjson::Value(Utf8FromUtf16(*clipboard_string), allocator), allocator);
+  result->Success(document);
+}
 
-    if (!clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()))) {
-      rapidjson::Document error_code;
-      error_code.SetInt(::GetLastError());
-      result->Error(kClipboardError, "Unable to open clipboard", error_code);
-      return;
-    }
-    if (!clipboard.SetString(Utf16FromUtf8(itr->value.GetString()))) {
-      rapidjson::Document error_code;
-      error_code.SetInt(::GetLastError());
-      result->Error(kClipboardError, "Unable to set clipboard data",
-                    error_code);
-      return;
-    }
-    result->Success();
-  } else {
-    result->NotImplemented();
+void PlatformHandlerWin32::SetPlainText(
+    const std::string& text,
+    std::unique_ptr<MethodResult<rapidjson::Document>> result) {
+  ScopedClipboard clipboard;
+  if (!clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()))) {
+    rapidjson::Document error_code;
+    error_code.SetInt(::GetLastError());
+    result->Error(kClipboardError, "Unable to open clipboard", error_code);
+    return;
+  }
+  if (!clipboard.SetString(Utf16FromUtf8(text))) {
+    rapidjson::Document error_code;
+    error_code.SetInt(::GetLastError());
+    result->Error(kClipboardError, "Unable to set clipboard data", error_code);
+    return;
   }
+  result->Success();
 }
 
 }  // namespace flutter
diff --git a/shell/platform/windows/platform_handler_win32.h b/shell/platform/windows/platform_handler_win32.h
new file mode 100644
index 0000000000000..c2879a1a4c4fd
--- /dev/null
+++ b/shell/platform/windows/platform_handler_win32.h
@@ -0,0 +1,43 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_WIN32_H_
+#define FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_WIN32_H_
+
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/binary_messenger.h"
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/method_channel.h"
+#include "flutter/shell/platform/windows/flutter_windows_view.h"
+#include "flutter/shell/platform/windows/platform_handler.h"
+#include "rapidjson/document.h"
+
+namespace flutter {
+
+class FlutterWindowsView;
+
+// Win32 implementation of PlatformHandler.
+class PlatformHandlerWin32 : public PlatformHandler {
+ public:
+  explicit PlatformHandlerWin32(BinaryMessenger* messenger,
+                                FlutterWindowsView* view);
+
+  virtual ~PlatformHandlerWin32();
+
+ protected:
+  // |PlatformHandler|
+  void GetPlainText(std::unique_ptr<MethodResult<rapidjson::Document>> result,
+                    const char* key) override;
+
+  // |PlatformHandler|
+  void SetPlainText(
+      const std::string& text,
+      std::unique_ptr<MethodResult<rapidjson::Document>> result) override;
+
+ private:
+  // A reference to the Flutter view.
+  FlutterWindowsView* view_;
+};
+
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_WIN32_H_
diff --git a/shell/platform/windows/platform_handler_winuwp.cc b/shell/platform/windows/platform_handler_winuwp.cc
new file mode 100644
index 0000000000000..cc3e3094302d4
--- /dev/null
+++ b/shell/platform/windows/platform_handler_winuwp.cc
@@ -0,0 +1,38 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/windows/platform_handler_winuwp.h"
+
+#include "flutter/shell/platform/windows/flutter_windows_view.h"
+
+namespace flutter {
+
+// static
+std::unique_ptr<PlatformHandler> PlatformHandler::Create(
+    BinaryMessenger* messenger,
+    FlutterWindowsView* view) {
+  return std::make_unique<PlatformHandlerWinUwp>(mesenger, view);
+}
+
+PlatformHandlerWinUwp::PlatformHandlerWinUwp(BinaryMessenger* messenger,
+                                             FlutterWindowsView* view)
+    : PlatformHandler(messenger), view_(view) {}
+
+PlatformHandlerWinUwp::~PlatformHandlerWinUwp() = default;
+
+void PlatformHandlerWinUwp::GetPlainText(
+    std::unique_ptr<MethodResult<rapidjson::Document>> result,
+    const char* key) {
+  // TODO: Implement. See https://github.com/flutter/flutter/issues/70214.
+  result->NotImplemented();
+}
+
+void PlatformHandlerWinUwp::SetPlainText(
+    const std::string& text,
+    std::unique_ptr<MethodResult<rapidjson::Document>> result) {
+  // TODO: Implement. See https://github.com/flutter/flutter/issues/70214.
+  result->NotImplemented();
+}
+
+}  // namespace flutter
diff --git a/shell/platform/windows/platform_handler_winuwp.h b/shell/platform/windows/platform_handler_winuwp.h
new file mode 100644
index 0000000000000..7a8a9ce504c6b
--- /dev/null
+++ b/shell/platform/windows/platform_handler_winuwp.h
@@ -0,0 +1,43 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_WINUWP_H_
+#define FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_WINUWP_H_
+
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/binary_messenger.h"
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/method_channel.h"
+#include "flutter/shell/platform/windows/flutter_windows_view.h"
+#include "flutter/shell/platform/windows/platform_handler.h"
+#include "rapidjson/document.h"
+
+namespace flutter {
+
+class FlutterWindowsView;
+
+// UWP implementation of PlatformHandler.
+class PlatformHandlerWinUwp : public PlatformHandler {
+ public:
+  explicit PlatformHandlerWinUwp(BinaryMessenger* messenger,
+                                 FlutterWindowsView* view);
+
+  virtual ~PlatformHandlerWinUwp();
+
+ protected:
+  // |PlatformHandler|
+  void GetPlainText(std::unique_ptr<MethodResult<rapidjson::Document>> result,
+                    const char* key) override;
+
+  // |PlatformHandler|
+  void SetPlainText(
+      const std::string& text,
+      std::unique_ptr<MethodResult<rapidjson::Document>> result) override;
+
+ private:
+  // A reference to the Flutter view.
+  FlutterWindowsView* view_;
+};
+
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_WINUWP_H_
diff --git a/shell/platform/windows/win32_platform_handler.h b/shell/platform/windows/win32_platform_handler.h
deleted file mode 100644
index bcf939edd4174..0000000000000
--- a/shell/platform/windows/win32_platform_handler.h
+++ /dev/null
@@ -1,38 +0,0 @@
-// Copyright 2013 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_H_
-#define FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_H_
-
-#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/binary_messenger.h"
-#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/method_channel.h"
-#include "flutter/shell/platform/windows/public/flutter_windows.h"
-#include "rapidjson/document.h"
-
-namespace flutter {
-
-class FlutterWindowsView;
-
-// Handler for internal system channels.
-class PlatformHandler {
- public:
-  explicit PlatformHandler(flutter::BinaryMessenger* messenger,
-                           FlutterWindowsView* view);
-
- private:
-  // Called when a method is called on |channel_|;
-  void HandleMethodCall(
-      const flutter::MethodCall<rapidjson::Document>& method_call,
-      std::unique_ptr<flutter::MethodResult<rapidjson::Document>> result);
-
-  // The MethodChannel used for communication with the Flutter engine.
-  std::unique_ptr<flutter::MethodChannel<rapidjson::Document>> channel_;
-
-  // A reference to the win32 window.
-  FlutterWindowsView* view_;
-};
-
-}  // namespace flutter
-
-#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_PLATFORM_HANDLER_H_

From e4c8484faa954e8d23487e15464030211ae30a44 Mon Sep 17 00:00:00 2001
From: Stuart Morgan <stuartmorgan@google.com>
Date: Mon, 23 Nov 2020 18:05:00 -0800
Subject: [PATCH 12/19] Do some testing backfill on the refactored
 PlatformHandler

---
 shell/platform/windows/BUILD.gn               |   2 +
 .../windows/platform_handler_unittests.cc     | 155 ++++++++++++++++++
 .../windows/testing/test_binary_messenger.h   |  80 +++++++++
 3 files changed, 237 insertions(+)
 create mode 100644 shell/platform/windows/platform_handler_unittests.cc
 create mode 100644 shell/platform/windows/testing/test_binary_messenger.h

diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index 86794d4d1b01e..ceda6261f20be 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -160,6 +160,7 @@ if (target_os == "winuwp") {
      sources = [
     "flutter_project_bundle_unittests.cc",
     "flutter_windows_engine_unittests.cc",
+    "platform_handler_unittests.cc",
     "string_conversion_unittests.cc",
     "system_utils_unittests.cc",
     "testing/engine_embedder_api_modifier.h",
@@ -179,6 +180,7 @@ if (target_os == "winuwp") {
     ":flutter_windows_fixtures",
     ":flutter_windows_headers",
     ":flutter_windows_source",
+    "//flutter/shell/platform/common/cpp:common_cpp",
     "//flutter/shell/platform/embedder:embedder_as_internal_library",
     "//flutter/shell/platform/embedder:embedder_test_utils",
     "//flutter/testing",
diff --git a/shell/platform/windows/platform_handler_unittests.cc b/shell/platform/windows/platform_handler_unittests.cc
new file mode 100644
index 0000000000000..78b348b8a84d0
--- /dev/null
+++ b/shell/platform/windows/platform_handler_unittests.cc
@@ -0,0 +1,155 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/windows/platform_handler.h"
+
+#include <memory>
+
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/binary_messenger.h"
+#include "flutter/shell/platform/common/cpp/json_method_codec.h"
+#include "flutter/shell/platform/windows/testing/test_binary_messenger.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "rapidjson/document.h"
+
+namespace flutter {
+namespace testing {
+
+namespace {
+using ::testing::_;
+
+static constexpr char kChannelName[] = "flutter/platform";
+
+static constexpr char kGetClipboardDataMethod[] = "Clipboard.getData";
+static constexpr char kSetClipboardDataMethod[] = "Clipboard.setData";
+
+static constexpr char kTextPlainFormat[] = "text/plain";
+
+// Test implementation of PlatformHandler to allow testing the PlatformHandler
+// logic.
+class TestPlatformHandler : public PlatformHandler {
+ public:
+  explicit TestPlatformHandler(BinaryMessenger* messenger)
+      : PlatformHandler(messenger) {}
+
+  virtual ~TestPlatformHandler() {}
+
+  // |PlatformHandler|
+  MOCK_METHOD2(GetPlainText,
+               void(std::unique_ptr<MethodResult<rapidjson::Document>>,
+                    const char*));
+  MOCK_METHOD2(SetPlainText,
+               void(const std::string&,
+                    std::unique_ptr<MethodResult<rapidjson::Document>>));
+};
+
+// Mock result to inspect results of PlatformHandler calls.
+class MockMethodResult : public MethodResult<rapidjson::Document> {
+ public:
+  MOCK_METHOD1(SuccessInternal, void(const rapidjson::Document*));
+  MOCK_METHOD3(ErrorInternal,
+               void(const std::string&,
+                    const std::string&,
+                    const rapidjson::Document*));
+  MOCK_METHOD0(NotImplementedInternal, void());
+};
+
+}  // namespace
+
+TEST(PlatformHandler, GettingTextCallsThrough) {
+  TestBinaryMessenger messenger;
+  TestPlatformHandler platform_handler(&messenger);
+
+  auto args = std::make_unique<rapidjson::Document>(rapidjson::kArrayType);
+  auto& allocator = args->GetAllocator();
+  args->PushBack(kTextPlainFormat, allocator);
+  auto encoded = JsonMethodCodec::GetInstance().EncodeMethodCall(
+      MethodCall<rapidjson::Document>(kGetClipboardDataMethod,
+                                      std::move(args)));
+
+  // Set up a handler to call a response on |result| so that it doesn't log
+  // on destruction about leaking.
+  ON_CALL(platform_handler, GetPlainText)
+      .WillByDefault(
+          [](std::unique_ptr<MethodResult<rapidjson::Document>> result,
+             auto key) { result->NotImplemented(); });
+
+  EXPECT_CALL(platform_handler, GetPlainText(_, ::testing::StrEq("text")));
+  EXPECT_TRUE(messenger.SimulateEngineMessage(
+      kChannelName, encoded->data(), encoded->size(),
+      [](const uint8_t* reply, size_t reply_size) {}));
+}
+
+TEST(PlatformHandler, RejectsGettingUnknownTypes) {
+  TestBinaryMessenger messenger;
+  TestPlatformHandler platform_handler(&messenger);
+
+  auto args = std::make_unique<rapidjson::Document>(rapidjson::kArrayType);
+  auto& allocator = args->GetAllocator();
+  args->PushBack("madeup/contenttype", allocator);
+  auto encoded = JsonMethodCodec::GetInstance().EncodeMethodCall(
+      MethodCall<rapidjson::Document>(kGetClipboardDataMethod,
+                                      std::move(args)));
+
+  MockMethodResult result;
+  // Requsting an unknow content type is an error.
+  EXPECT_CALL(result, ErrorInternal(_, _, _));
+  EXPECT_TRUE(messenger.SimulateEngineMessage(
+      kChannelName, encoded->data(), encoded->size(),
+      [&](const uint8_t* reply, size_t reply_size) {
+        JsonMethodCodec::GetInstance().DecodeAndProcessResponseEnvelope(
+            reply, reply_size, &result);
+      }));
+}
+
+TEST(PlatformHandler, SettingTextCallsThrough) {
+  TestBinaryMessenger messenger;
+  TestPlatformHandler platform_handler(&messenger);
+
+  auto args = std::make_unique<rapidjson::Document>(rapidjson::kObjectType);
+  auto& allocator = args->GetAllocator();
+  args->AddMember("text", "hello", allocator);
+  auto encoded = JsonMethodCodec::GetInstance().EncodeMethodCall(
+      MethodCall<rapidjson::Document>(kSetClipboardDataMethod,
+                                      std::move(args)));
+
+  // Set up a handler to call a response on |result| so that it doesn't log
+  // on destruction about leaking.
+  ON_CALL(platform_handler, SetPlainText)
+      .WillByDefault(
+          [](auto value,
+             std::unique_ptr<MethodResult<rapidjson::Document>> result) {
+            result->NotImplemented();
+          });
+
+  EXPECT_CALL(platform_handler, SetPlainText(::testing::StrEq("hello"), _));
+  EXPECT_TRUE(messenger.SimulateEngineMessage(
+      kChannelName, encoded->data(), encoded->size(),
+      [](const uint8_t* reply, size_t reply_size) {}));
+}
+
+TEST(PlatformHandler, RejectsSettingUnknownTypes) {
+  TestBinaryMessenger messenger;
+  TestPlatformHandler platform_handler(&messenger);
+
+  auto args = std::make_unique<rapidjson::Document>(rapidjson::kObjectType);
+  auto& allocator = args->GetAllocator();
+  args->AddMember("madeuptype", "hello", allocator);
+  auto encoded = JsonMethodCodec::GetInstance().EncodeMethodCall(
+      MethodCall<rapidjson::Document>(kSetClipboardDataMethod,
+                                      std::move(args)));
+
+  MockMethodResult result;
+  // Requsting an unknow content type is an error.
+  EXPECT_CALL(result, ErrorInternal(_, _, _));
+  EXPECT_TRUE(messenger.SimulateEngineMessage(
+      kChannelName, encoded->data(), encoded->size(),
+      [&](const uint8_t* reply, size_t reply_size) {
+        JsonMethodCodec::GetInstance().DecodeAndProcessResponseEnvelope(
+            reply, reply_size, &result);
+      }));
+}
+
+}  // namespace testing
+}  // namespace flutter
diff --git a/shell/platform/windows/testing/test_binary_messenger.h b/shell/platform/windows/testing/test_binary_messenger.h
new file mode 100644
index 0000000000000..157a1e8f1f12d
--- /dev/null
+++ b/shell/platform/windows/testing/test_binary_messenger.h
@@ -0,0 +1,80 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_TEST_BINARY_MESSENGER_H_
+#define FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_TEST_BINARY_MESSENGER_H_
+
+#include <cassert>
+#include <functional>
+#include <map>
+#include <string>
+
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/binary_messenger.h"
+
+namespace flutter {
+
+// A trivial BinaryMessenger implementation for use in tests.
+class TestBinaryMessenger : public BinaryMessenger {
+ public:
+  using SendHandler = std::function<void(const std::string& channel,
+                                         const uint8_t* message,
+                                         size_t message_size,
+                                         BinaryReply reply)>;
+
+  // Creates a new messenge that forwards all calls to |send_handler|.
+  explicit TestBinaryMessenger(SendHandler send_handler = nullptr)
+      : send_handler_(std::move(send_handler)) {}
+
+  virtual ~TestBinaryMessenger() = default;
+
+  // Prevent copying.
+  TestBinaryMessenger(TestBinaryMessenger const&) = delete;
+  TestBinaryMessenger& operator=(TestBinaryMessenger const&) = delete;
+
+  // Simulates a message from the engine on the given channel.
+  //
+  // Returns false if no handler is registered on that channel.
+  bool SimulateEngineMessage(const std::string& channel,
+                             const uint8_t* message,
+                             size_t message_size,
+                             BinaryReply reply) {
+    auto handler = registered_handlers_.find(channel);
+    if (handler == registered_handlers_.end()) {
+      return false;
+    }
+    (handler->second)(message, message_size, reply);
+    return true;
+  }
+
+  // |flutter::BinaryMessenger|
+  void Send(const std::string& channel,
+            const uint8_t* message,
+            size_t message_size,
+            BinaryReply reply) const override {
+    // If something under test sends a message, the test should be handling it.
+    assert(send_handler_);
+    send_handler_(channel, message, message_size, reply);
+  }
+
+  // |flutter::BinaryMessenger|
+  void SetMessageHandler(const std::string& channel,
+                         BinaryMessageHandler handler) override {
+    if (handler) {
+      registered_handlers_[channel] = handler;
+    } else {
+      registered_handlers_.erase(channel);
+    }
+  }
+
+ private:
+  // Handler to call for SendMessage.
+  SendHandler send_handler_;
+
+  // Mapping of channel name to registered handlers.
+  std::map<std::string, BinaryMessageHandler> registered_handlers_;
+};
+
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_TEST_BINARY_MESSENGER_H_

From 895088c8531bf55824518d4b3eac2185701e01e0 Mon Sep 17 00:00:00 2001
From: Stuart Morgan <stuartmorgan@google.com>
Date: Mon, 23 Nov 2020 18:08:05 -0800
Subject: [PATCH 13/19] Formatting

---
 shell/platform/windows/BUILD.gn               | 77 +++++++++++--------
 .../platform/windows/client_wrapper/BUILD.gn  |  9 ++-
 .../platform/windows/public/flutter_windows.h |  2 +-
 3 files changed, 50 insertions(+), 38 deletions(-)

diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index ceda6261f20be..2433913868113 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -26,8 +26,9 @@ config("relative_flutter_windows_headers") {
 source_set("flutter_windows_headers") {
   public = _public_headers
 
-  public_deps =
-      [ "//flutter/shell/platform/common/cpp:common_cpp_library_headers" ]
+  public_deps = [
+    "//flutter/shell/platform/common/cpp:common_cpp_library_headers",
+  ]
 
   if (target_os == "winuwp") {
     configs +=
@@ -129,20 +130,28 @@ source_set("flutter_windows_source") {
 
 copy("publish_headers_windows") {
   sources = _public_headers
-  outputs = [ "$root_out_dir/{{source_file_part}}" ]
+  outputs = [
+    "$root_out_dir/{{source_file_part}}",
+  ]
 
   # The Windows header assumes the presence of the common headers.
-  deps = [ "//flutter/shell/platform/common/cpp:publish_headers" ]
+  deps = [
+    "//flutter/shell/platform/common/cpp:publish_headers",
+  ]
 }
 
 shared_library("flutter_windows") {
-  deps = [ ":flutter_windows_source" ]
+  deps = [
+    ":flutter_windows_source",
+  ]
 
   public_configs = [ "//flutter:config" ]
 }
 
 shared_library("flutter_windows_winuwp") {
-  deps = [ ":flutter_windows_source" ]
+  deps = [
+    ":flutter_windows_source",
+  ]
   libs = [ "windowsapp.lib" ]
   public_configs = [ "//flutter:config" ]
 }
@@ -157,40 +166,42 @@ if (target_os == "winuwp") {
   executable("flutter_windows_unittests") {
     testonly = true
 
-     sources = [
-    "flutter_project_bundle_unittests.cc",
-    "flutter_windows_engine_unittests.cc",
-    "platform_handler_unittests.cc",
-    "string_conversion_unittests.cc",
-    "system_utils_unittests.cc",
-    "testing/engine_embedder_api_modifier.h",
-    "testing/mock_win32_window.cc",
-    "testing/mock_win32_window.h",
-    "testing/win32_flutter_window_test.cc",
-    "testing/win32_flutter_window_test.h",
-    "win32_dpi_utils_unittests.cc",
-    "win32_flutter_window_unittests.cc",
-    "win32_window_proc_delegate_manager_unittests.cc",
-    "win32_window_unittests.cc",
-  ]
+    sources = [
+      "flutter_project_bundle_unittests.cc",
+      "flutter_windows_engine_unittests.cc",
+      "platform_handler_unittests.cc",
+      "string_conversion_unittests.cc",
+      "system_utils_unittests.cc",
+      "testing/engine_embedder_api_modifier.h",
+      "testing/mock_win32_window.cc",
+      "testing/mock_win32_window.h",
+      "testing/win32_flutter_window_test.cc",
+      "testing/win32_flutter_window_test.h",
+      "win32_dpi_utils_unittests.cc",
+      "win32_flutter_window_unittests.cc",
+      "win32_window_proc_delegate_manager_unittests.cc",
+      "win32_window_unittests.cc",
+    ]
 
     public_configs = [ "//flutter:config" ]
 
-   deps = [
-    ":flutter_windows_fixtures",
-    ":flutter_windows_headers",
-    ":flutter_windows_source",
-    "//flutter/shell/platform/common/cpp:common_cpp",
-    "//flutter/shell/platform/embedder:embedder_as_internal_library",
-    "//flutter/shell/platform/embedder:embedder_test_utils",
-    "//flutter/testing",
-    "//third_party/rapidjson",
-  ]
+    deps = [
+      ":flutter_windows_fixtures",
+      ":flutter_windows_headers",
+      ":flutter_windows_source",
+      "//flutter/shell/platform/common/cpp:common_cpp",
+      "//flutter/shell/platform/embedder:embedder_as_internal_library",
+      "//flutter/shell/platform/embedder:embedder_test_utils",
+      "//flutter/testing",
+      "//third_party/rapidjson",
+    ]
   }
 }
 
 shared_library("flutter_windows_glfw") {
-  deps = [ "//flutter/shell/platform/glfw:flutter_glfw" ]
+  deps = [
+    "//flutter/shell/platform/glfw:flutter_glfw",
+  ]
 
   public_configs = [ "//flutter:config" ]
 }
diff --git a/shell/platform/windows/client_wrapper/BUILD.gn b/shell/platform/windows/client_wrapper/BUILD.gn
index 15fc0d4c16d33..50e15613e82a7 100644
--- a/shell/platform/windows/client_wrapper/BUILD.gn
+++ b/shell/platform/windows/client_wrapper/BUILD.gn
@@ -39,9 +39,8 @@ source_set("client_wrapper_windows") {
     "//flutter/shell/platform/windows:flutter_windows_headers",
   ]
 
-  configs += [
-    "//flutter/shell/platform/common/cpp:desktop_library_implementation",
-  ]
+  configs +=
+      [ "//flutter/shell/platform/common/cpp:desktop_library_implementation" ]
 
   public_configs = [
     ":relative_core_wrapper_headers",
@@ -64,7 +63,9 @@ source_set("client_wrapper_library_stubs_windows") {
 
   defines = [ "FLUTTER_DESKTOP_LIBRARY" ]
 
-  public_deps = [ "//flutter/shell/platform/windows:flutter_windows_headers" ]
+  public_deps = [
+    "//flutter/shell/platform/windows:flutter_windows_headers",
+  ]
 }
 
 test_fixtures("client_wrapper_windows_fixtures") {
diff --git a/shell/platform/windows/public/flutter_windows.h b/shell/platform/windows/public/flutter_windows.h
index 54cb5d905e338..dbcaf8df17035 100644
--- a/shell/platform/windows/public/flutter_windows.h
+++ b/shell/platform/windows/public/flutter_windows.h
@@ -92,7 +92,7 @@ FLUTTER_EXPORT FlutterDesktopEngineRef FlutterDesktopViewControllerGetEngine(
 FLUTTER_EXPORT FlutterDesktopViewRef
 FlutterDesktopViewControllerGetView(FlutterDesktopViewControllerRef controller);
 
-  #ifndef WINUWP
+#ifndef WINUWP
 // Allows the Flutter engine and any interested plugins an opportunity to
 // handle the given message.
 //

From 111063c18c936495aa69e1792fcaad7c2b2a3e8b Mon Sep 17 00:00:00 2001
From: Stuart Morgan <stuartmorgan@google.com>
Date: Tue, 24 Nov 2020 09:36:23 -0800
Subject: [PATCH 14/19] Formatting again, but with the right gn

---
 shell/platform/windows/BUILD.gn               | 25 ++++++-------------
 .../platform/windows/client_wrapper/BUILD.gn  |  4 +--
 .../include/flutter/flutter_view_controller.h |  2 +-
 3 files changed, 9 insertions(+), 22 deletions(-)

diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index 2433913868113..b1a9dc519f1a9 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -26,9 +26,8 @@ config("relative_flutter_windows_headers") {
 source_set("flutter_windows_headers") {
   public = _public_headers
 
-  public_deps = [
-    "//flutter/shell/platform/common/cpp:common_cpp_library_headers",
-  ]
+  public_deps =
+      [ "//flutter/shell/platform/common/cpp:common_cpp_library_headers" ]
 
   if (target_os == "winuwp") {
     configs +=
@@ -130,28 +129,20 @@ source_set("flutter_windows_source") {
 
 copy("publish_headers_windows") {
   sources = _public_headers
-  outputs = [
-    "$root_out_dir/{{source_file_part}}",
-  ]
+  outputs = [ "$root_out_dir/{{source_file_part}}" ]
 
   # The Windows header assumes the presence of the common headers.
-  deps = [
-    "//flutter/shell/platform/common/cpp:publish_headers",
-  ]
+  deps = [ "//flutter/shell/platform/common/cpp:publish_headers" ]
 }
 
 shared_library("flutter_windows") {
-  deps = [
-    ":flutter_windows_source",
-  ]
+  deps = [ ":flutter_windows_source" ]
 
   public_configs = [ "//flutter:config" ]
 }
 
 shared_library("flutter_windows_winuwp") {
-  deps = [
-    ":flutter_windows_source",
-  ]
+  deps = [ ":flutter_windows_source" ]
   libs = [ "windowsapp.lib" ]
   public_configs = [ "//flutter:config" ]
 }
@@ -199,9 +190,7 @@ if (target_os == "winuwp") {
 }
 
 shared_library("flutter_windows_glfw") {
-  deps = [
-    "//flutter/shell/platform/glfw:flutter_glfw",
-  ]
+  deps = [ "//flutter/shell/platform/glfw:flutter_glfw" ]
 
   public_configs = [ "//flutter:config" ]
 }
diff --git a/shell/platform/windows/client_wrapper/BUILD.gn b/shell/platform/windows/client_wrapper/BUILD.gn
index 50e15613e82a7..fe54c2ba2a484 100644
--- a/shell/platform/windows/client_wrapper/BUILD.gn
+++ b/shell/platform/windows/client_wrapper/BUILD.gn
@@ -63,9 +63,7 @@ source_set("client_wrapper_library_stubs_windows") {
 
   defines = [ "FLUTTER_DESKTOP_LIBRARY" ]
 
-  public_deps = [
-    "//flutter/shell/platform/windows:flutter_windows_headers",
-  ]
+  public_deps = [ "//flutter/shell/platform/windows:flutter_windows_headers" ]
 }
 
 test_fixtures("client_wrapper_windows_fixtures") {
diff --git a/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h b/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h
index 6a21af0922b81..f39a7e70c980e 100644
--- a/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h
+++ b/shell/platform/windows/client_wrapper/include/flutter/flutter_view_controller.h
@@ -56,7 +56,7 @@ class FlutterViewController {
                                                   UINT message,
                                                   WPARAM wparam,
                                                   LPARAM lparam);
-  #endif
+#endif
 
  private:
   // Handle for interacting with the C API's view controller, if any.

From 26f2b5578041ed8fbee66ba8fa6b1538c21d7880 Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Sat, 5 Dec 2020 06:23:55 -0800
Subject: [PATCH 15/19] Fix UWP build

---
 .../platform/windows/platform_handler_winuwp.cc  |  2 +-
 shell/platform/windows/system_utils_winuwp.cc    | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/shell/platform/windows/platform_handler_winuwp.cc b/shell/platform/windows/platform_handler_winuwp.cc
index cc3e3094302d4..f109c3819713b 100644
--- a/shell/platform/windows/platform_handler_winuwp.cc
+++ b/shell/platform/windows/platform_handler_winuwp.cc
@@ -12,7 +12,7 @@ namespace flutter {
 std::unique_ptr<PlatformHandler> PlatformHandler::Create(
     BinaryMessenger* messenger,
     FlutterWindowsView* view) {
-  return std::make_unique<PlatformHandlerWinUwp>(mesenger, view);
+  return std::make_unique<PlatformHandlerWinUwp>(messenger, view);
 }
 
 PlatformHandlerWinUwp::PlatformHandlerWinUwp(BinaryMessenger* messenger,
diff --git a/shell/platform/windows/system_utils_winuwp.cc b/shell/platform/windows/system_utils_winuwp.cc
index 4d693def5a758..85278dc0a6dd5 100644
--- a/shell/platform/windows/system_utils_winuwp.cc
+++ b/shell/platform/windows/system_utils_winuwp.cc
@@ -32,4 +32,20 @@ LanguageInfo ParseLanguageName(std::wstring language_name) {
   return info;
 }
 
+std::wstring GetUserTimeFormat() {
+  // Rather than do the call-allocate-call-free dance, just use a sufficiently
+  // large buffer to handle any reasonable time format string.
+  const int kBufferSize = 100;
+  wchar_t buffer[kBufferSize];
+  if (::GetLocaleInfoEx(LOCALE_NAME_USER_DEFAULT, LOCALE_STIMEFORMAT, buffer,
+                        kBufferSize) == 0) {
+    return std::wstring();
+  }
+  return std::wstring(buffer, kBufferSize);
+}
+
+bool Prefer24HourTime(std::wstring time_format) {
+  return time_format.find(L"H") != std::wstring::npos;
+}
+
 }  // namespace flutter

From 59d6d53d1161d257fcd263847c66a0f5f943ebb7 Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Sat, 5 Dec 2020 07:00:53 -0800
Subject: [PATCH 16/19] Fix the win32 build

---
 shell/platform/windows/BUILD.gn | 1 -
 1 file changed, 1 deletion(-)

diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index b1a9dc519f1a9..873125ad4ebef 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -160,7 +160,6 @@ if (target_os == "winuwp") {
     sources = [
       "flutter_project_bundle_unittests.cc",
       "flutter_windows_engine_unittests.cc",
-      "platform_handler_unittests.cc",
       "string_conversion_unittests.cc",
       "system_utils_unittests.cc",
       "testing/engine_embedder_api_modifier.h",

From 81b31d7861e3951f910812dedc29d471bcd4f8b2 Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Sat, 5 Dec 2020 07:14:26 -0800
Subject: [PATCH 17/19] CR feedback

---
 shell/platform/windows/platform_handler.h         | 2 +-
 shell/platform/windows/platform_handler_win32.cc  | 4 ++--
 shell/platform/windows/platform_handler_win32.h   | 2 +-
 shell/platform/windows/platform_handler_winuwp.cc | 2 +-
 shell/platform/windows/platform_handler_winuwp.h  | 2 +-
 5 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/shell/platform/windows/platform_handler.h b/shell/platform/windows/platform_handler.h
index ba5a86ea0d8ed..b7268023a8e21 100644
--- a/shell/platform/windows/platform_handler.h
+++ b/shell/platform/windows/platform_handler.h
@@ -29,7 +29,7 @@ class PlatformHandler {
   // value in a dictionary with the given |key|.
   virtual void GetPlainText(
       std::unique_ptr<MethodResult<rapidjson::Document>> result,
-      const char* key) = 0;
+      std::string_view key) = 0;
 
   // Sets the clipboard's plain text to |text|, and reports the result (either
   // an error, or null for success) to |result|.
diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index f891bd540421a..b4f0ea351601e 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -200,7 +200,7 @@ PlatformHandlerWin32::~PlatformHandlerWin32() = default;
 
 void PlatformHandlerWin32::GetPlainText(
     std::unique_ptr<MethodResult<rapidjson::Document>> result,
-    const char* key) {
+    std::string_view key) {
   ScopedClipboard clipboard;
   if (!clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()))) {
     rapidjson::Document error_code;
@@ -224,7 +224,7 @@ void PlatformHandlerWin32::GetPlainText(
   document.SetObject();
   rapidjson::Document::AllocatorType& allocator = document.GetAllocator();
   document.AddMember(
-      rapidjson::Value(key, allocator),
+      rapidjson::Value(key.data(), allocator),
       rapidjson::Value(Utf8FromUtf16(*clipboard_string), allocator), allocator);
   result->Success(document);
 }
diff --git a/shell/platform/windows/platform_handler_win32.h b/shell/platform/windows/platform_handler_win32.h
index c2879a1a4c4fd..ad8ec92ed5e37 100644
--- a/shell/platform/windows/platform_handler_win32.h
+++ b/shell/platform/windows/platform_handler_win32.h
@@ -26,7 +26,7 @@ class PlatformHandlerWin32 : public PlatformHandler {
  protected:
   // |PlatformHandler|
   void GetPlainText(std::unique_ptr<MethodResult<rapidjson::Document>> result,
-                    const char* key) override;
+                    std::string_view key) override;
 
   // |PlatformHandler|
   void SetPlainText(
diff --git a/shell/platform/windows/platform_handler_winuwp.cc b/shell/platform/windows/platform_handler_winuwp.cc
index f109c3819713b..e984d1fc9fd79 100644
--- a/shell/platform/windows/platform_handler_winuwp.cc
+++ b/shell/platform/windows/platform_handler_winuwp.cc
@@ -23,7 +23,7 @@ PlatformHandlerWinUwp::~PlatformHandlerWinUwp() = default;
 
 void PlatformHandlerWinUwp::GetPlainText(
     std::unique_ptr<MethodResult<rapidjson::Document>> result,
-    const char* key) {
+    std::string_view key) {
   // TODO: Implement. See https://github.com/flutter/flutter/issues/70214.
   result->NotImplemented();
 }
diff --git a/shell/platform/windows/platform_handler_winuwp.h b/shell/platform/windows/platform_handler_winuwp.h
index 7a8a9ce504c6b..f8b2b221e1961 100644
--- a/shell/platform/windows/platform_handler_winuwp.h
+++ b/shell/platform/windows/platform_handler_winuwp.h
@@ -26,7 +26,7 @@ class PlatformHandlerWinUwp : public PlatformHandler {
  protected:
   // |PlatformHandler|
   void GetPlainText(std::unique_ptr<MethodResult<rapidjson::Document>> result,
-                    const char* key) override;
+                    std::string_view key) override;
 
   // |PlatformHandler|
   void SetPlainText(

From 15d6fb64816305aaad5044ea3cb218f28170fa47 Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Sat, 5 Dec 2020 07:48:13 -0800
Subject: [PATCH 18/19] Make licenses happy again

---
 ci/licenses_golden/licenses_flutter | 1 +
 1 file changed, 1 insertion(+)

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index d246a264799f7..c97e31f0ec04e 100755
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -1415,6 +1415,7 @@ FILE: ../../../flutter/shell/platform/windows/key_event_handler.h
 FILE: ../../../flutter/shell/platform/windows/keyboard_hook_handler.h
 FILE: ../../../flutter/shell/platform/windows/platform_handler.cc
 FILE: ../../../flutter/shell/platform/windows/platform_handler.h
+FILE: ../../../flutter/shell/platform/windows/platform_handler_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/platform_handler_win32.cc
 FILE: ../../../flutter/shell/platform/windows/platform_handler_win32.h
 FILE: ../../../flutter/shell/platform/windows/platform_handler_winuwp.cc

From a4a43c6c8f4af1bda83cf7b9e81687f89c12391e Mon Sep 17 00:00:00 2001
From: James Clarke <james@clarkezone.net>
Date: Sat, 5 Dec 2020 08:08:43 -0800
Subject: [PATCH 19/19] Make licenses happy again take 2

---
 ci/licenses_golden/licenses_flutter | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index c97e31f0ec04e..e87e78e4dbadd 100755
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -1403,13 +1403,13 @@ FILE: ../../../flutter/shell/platform/windows/flutter_project_bundle.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_project_bundle.h
 FILE: ../../../flutter/shell/platform/windows/flutter_project_bundle_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_windows.cc
-FILE: ../../../flutter/shell/platform/windows/flutter_windows_win32.cc
-FILE: ../../../flutter/shell/platform/windows/flutter_windows_winuwp.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_windows_engine.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_windows_engine.h
 FILE: ../../../flutter/shell/platform/windows/flutter_windows_engine_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_windows_view.cc
 FILE: ../../../flutter/shell/platform/windows/flutter_windows_view.h
+FILE: ../../../flutter/shell/platform/windows/flutter_windows_win32.cc
+FILE: ../../../flutter/shell/platform/windows/flutter_windows_winuwp.cc
 FILE: ../../../flutter/shell/platform/windows/key_event_handler.cc
 FILE: ../../../flutter/shell/platform/windows/key_event_handler.h
 FILE: ../../../flutter/shell/platform/windows/keyboard_hook_handler.h