Windows: Add UWP target stub [Flutter#14697]

BUILD.gn

@@ -152,10 +152,15 @@ group("flutter") {
       }
 
       if (is_win) {
-        public_deps += [
-          "//flutter/shell/platform/windows:flutter_windows_unittests",
-          "//flutter/shell/platform/windows/client_wrapper:client_wrapper_windows_unittests",
-        ]
+        if (target_os == "winuwp") {
+          # 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",
+            "//flutter/shell/platform/windows/client_wrapper:client_wrapper_windows_unittests",
+          ]
+        }
       }
     }
   }

ci/licenses_golden/licenses_flutter

@@ -1408,16 +1408,31 @@ 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
+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
+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
 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/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
@@ -1426,10 +1441,6 @@ 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_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

shell/platform/windows/BUILD.gn

@@ -29,14 +29,20 @@ 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" ]
+  } else {
+    configs +=
+        [ "//flutter/shell/platform/common/cpp:desktop_library_implementation" ]
+  }
 
   public_configs =
       [ "//flutter/shell/platform/common/cpp:relative_flutter_library_headers" ]
 }
 
 source_set("flutter_windows_source") {
+  # Common Windows sources.
   sources = [
     "angle_surface_manager.cc",
     "angle_surface_manager.h",
@@ -52,29 +58,48 @@ 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",
-    "system_utils_win32.cc",
+    "task_runner.h",
     "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",
   ]
 
+  # Target-specific sources.
+  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",
+    ]
+  } 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",
+      "win32_dpi_utils.cc",
+      "win32_dpi_utils.h",
+      "win32_flutter_window.cc",
+      "win32_flutter_window.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",
@@ -116,40 +141,51 @@ shared_library("flutter_windows") {
   public_configs = [ "//flutter:config" ]
 }
 
+shared_library("flutter_windows_winuwp") {
+  deps = [ ":flutter_windows_source" ]
+  libs = [ "windowsapp.lib" ]
+  public_configs = [ "//flutter:config" ]
+}
+
 test_fixtures("flutter_windows_fixtures") {
   fixtures = []
 }
 
-executable("flutter_windows_unittests") {
-  testonly = true
-
-  sources = [
-    "flutter_project_bundle_unittests.cc",
-    "flutter_windows_engine_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/embedder:embedder_as_internal_library",
-    "//flutter/shell/platform/embedder:embedder_test_utils",
-    "//flutter/testing",
-    "//third_party/rapidjson",
-  ]
+if (target_os == "winuwp") {
+  # disabled until the uwp implementation is present
+} else {
+  executable("flutter_windows_unittests") {
+    testonly = true
+
+    sources = [
+      "flutter_project_bundle_unittests.cc",
+      "flutter_windows_engine_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",
+    ]
+  }
 }
 
 shared_library("flutter_windows_glfw") {
@@ -168,11 +204,20 @@ 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" ]
   }

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_);

shell/platform/windows/client_wrapper/flutter_view_controller.cc

@@ -29,6 +29,7 @@ FlutterViewController::~FlutterViewController() {
   }
 }
 
+#ifndef 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

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 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.

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 {