Delete unused/test only code from FML (#48327)

This is more-or-less a revert of #14011

This code never ended up being used outside of tests, and it's not how we handle asset loading at this point anyway.

I was hopeful we could kill off all runtime dependencies on Dart in `FML` when looking at this, but it looks like trace_event.h still wants to import dart_api_tools.h for some Dart enum types. This may or may not matter if we ever want to build FML for web/wasm. /cc @eyebrowsoffire. If we really need to do that, we can refactor the trace event stuff so that it has a web and Dart implementation that's selected at build time.

Author: dnfield

ci/licenses_golden/licenses_flutter

@@ -4697,8 +4697,6 @@ ORIGIN: ../../../flutter/fml/concurrent_message_loop_factory.cc + ../../../flutt
 ORIGIN: ../../../flutter/fml/container.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/fml/cpu_affinity.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/fml/cpu_affinity.h + ../../../flutter/LICENSE
-ORIGIN: ../../../flutter/fml/dart/dart_converter.cc + ../../../flutter/LICENSE
-ORIGIN: ../../../flutter/fml/dart/dart_converter.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/fml/delayed_task.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/fml/delayed_task.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/fml/eintr_wrapper.h + ../../../flutter/LICENSE
@@ -7471,8 +7469,6 @@ FILE: ../../../flutter/fml/concurrent_message_loop_factory.cc
 FILE: ../../../flutter/fml/container.h
 FILE: ../../../flutter/fml/cpu_affinity.cc
 FILE: ../../../flutter/fml/cpu_affinity.h
-FILE: ../../../flutter/fml/dart/dart_converter.cc
-FILE: ../../../flutter/fml/dart/dart_converter.h
 FILE: ../../../flutter/fml/delayed_task.cc
 FILE: ../../../flutter/fml/delayed_task.h
 FILE: ../../../flutter/fml/eintr_wrapper.h

fml/BUILD.gn

@@ -387,7 +387,6 @@ if (enable_unittests) {
     deps = [
       ":fml_fixtures",
       "//flutter/fml",
-      "//flutter/fml/dart",
       "//flutter/runtime",
       "//flutter/runtime:libdart",
       "//flutter/testing",

fml/dart/BUILD.gn

@@ -245,7 +245,6 @@ if (enable_unittests) {
     public_deps = [
       "//flutter/common/graphics",
       "//flutter/flow",
-      "//flutter/fml/dart",
       "//flutter/runtime",
       "//flutter/shell/common",
       "//flutter/testing",

fml/dart/dart_converter.cc

@@ -220,29 +220,6 @@ void callNotifyDestroyed() {
 @pragma('vm:external-name', 'NotifyMessage')
 external void notifyMessage(String string);
 
-@pragma('vm:entry-point')
-void canConvertMappings() {
-  sendFixtureMapping(getFixtureMapping());
-}
-
-@pragma('vm:external-name', 'GetFixtureMapping')
-external List<int> getFixtureMapping();
-@pragma('vm:external-name', 'SendFixtureMapping')
-external void sendFixtureMapping(List<int> list);
-
-@pragma('vm:entry-point')
-void canDecompressImageFromAsset() {
-  decodeImageFromList(
-    Uint8List.fromList(getFixtureImage()),
-    (Image result) {
-      notifyWidthHeight(result.width, result.height);
-    },
-  );
-}
-
-@pragma('vm:external-name', 'GetFixtureImage')
-external List<int> getFixtureImage();
-
 @pragma('vm:entry-point')
 void canRegisterImageDecoders() {
   decodeImageFromList(

fml/dart/dart_converter.h

@@ -18,7 +18,6 @@
 #include <fuchsia/settings/cpp/fidl.h>
 #include <lib/sys/cpp/component_context.h>
 
-#include "flutter/fml/dart/dart_converter.h"
 #include "flutter/fml/logging.h"
 #include "flutter/fml/synchronization/count_down_latch.h"
 #include "flutter/runtime/dart_vm.h"

shell/common/BUILD.gn

@@ -28,7 +28,6 @@
 #include "flutter/flow/layers/transform_layer.h"
 #include "flutter/fml/backtrace.h"
 #include "flutter/fml/command_line.h"
-#include "flutter/fml/dart/dart_converter.h"
 #include "flutter/fml/make_copyable.h"
 #include "flutter/fml/message_loop.h"
 #include "flutter/fml/synchronization/count_down_latch.h"
@@ -2207,52 +2206,6 @@ TEST_F(ShellTest, Screenshot) {
   DestroyShell(std::move(shell));
 }
 
-TEST_F(ShellTest, CanConvertToAndFromMappings) {
-  const size_t buffer_size = 2 << 20;
-
-  uint8_t* buffer = static_cast<uint8_t*>(::malloc(buffer_size));
-  // NOLINTNEXTLINE(clang-analyzer-unix.Malloc)
-  ASSERT_TRUE(buffer != nullptr);
-  ASSERT_TRUE(MemsetPatternSetOrCheck(
-      buffer, buffer_size, MemsetPatternOp::kMemsetPatternOpSetBuffer));
-
-  std::unique_ptr<fml::Mapping> mapping =
-      std::make_unique<fml::MallocMapping>(buffer, buffer_size);
-
-  ASSERT_EQ(mapping->GetSize(), buffer_size);
-
-  fml::AutoResetWaitableEvent latch;
-  AddNativeCallback(
-      "SendFixtureMapping", CREATE_NATIVE_ENTRY([&](auto args) {
-        auto mapping_from_dart =
-            tonic::DartConverter<std::unique_ptr<fml::Mapping>>::FromDart(
-                Dart_GetNativeArgument(args, 0));
-        ASSERT_NE(mapping_from_dart, nullptr);
-        ASSERT_EQ(mapping_from_dart->GetSize(), buffer_size);
-        ASSERT_TRUE(MemsetPatternSetOrCheck(
-            const_cast<uint8_t*>(mapping_from_dart->GetMapping()),  // buffer
-            mapping_from_dart->GetSize(),                           // size
-            MemsetPatternOp::kMemsetPatternOpCheckBuffer            // op
-            ));
-        latch.Signal();
-      }));
-
-  AddNativeCallback(
-      "GetFixtureMapping", CREATE_NATIVE_ENTRY([&](auto args) {
-        tonic::DartConverter<tonic::DartConverterMapping>::SetReturnValue(
-            args, mapping);
-      }));
-
-  auto settings = CreateSettingsForFixture();
-  auto configuration = RunConfiguration::InferFromSettings(settings);
-  configuration.SetEntrypoint("canConvertMappings");
-  std::unique_ptr<Shell> shell = CreateShell(settings);
-  ASSERT_NE(shell.get(), nullptr);
-  RunEngine(shell.get(), std::move(configuration));
-  latch.Wait();
-  DestroyShell(std::move(shell));
-}
-
 // Compares local times as seen by the dart isolate and as seen by this test
 // fixture, to a resolution of 1 hour.
 //
@@ -2301,35 +2254,6 @@ TEST_F(ShellTest, LocaltimesMatch) {
   DestroyShell(std::move(shell));
 }
 
-TEST_F(ShellTest, CanDecompressImageFromAsset) {
-  fml::AutoResetWaitableEvent latch;
-  AddNativeCallback("NotifyWidthHeight", CREATE_NATIVE_ENTRY([&](auto args) {
-                      auto width = tonic::DartConverter<int>::FromDart(
-                          Dart_GetNativeArgument(args, 0));
-                      auto height = tonic::DartConverter<int>::FromDart(
-                          Dart_GetNativeArgument(args, 1));
-                      ASSERT_EQ(width, 100);
-                      ASSERT_EQ(height, 100);
-                      latch.Signal();
-                    }));
-
-  AddNativeCallback(
-      "GetFixtureImage", CREATE_NATIVE_ENTRY([](auto args) {
-        auto fixture = OpenFixtureAsMapping("shelltest_screenshot.png");
-        tonic::DartConverter<tonic::DartConverterMapping>::SetReturnValue(
-            args, fixture);
-      }));
-
-  auto settings = CreateSettingsForFixture();
-  auto configuration = RunConfiguration::InferFromSettings(settings);
-  configuration.SetEntrypoint("canDecompressImageFromAsset");
-  std::unique_ptr<Shell> shell = CreateShell(settings);
-  ASSERT_NE(shell.get(), nullptr);
-  RunEngine(shell.get(), std::move(configuration));
-  latch.Wait();
-  DestroyShell(std::move(shell));
-}
-
 /// An image generator that always creates a 1x1 single-frame green image.
 class SinglePixelImageGenerator : public ImageGenerator {
  public:

shell/common/fixtures/shell_test.dart

@@ -105,7 +105,6 @@ if (is_mac) {
              ":gpu_surface_metal",
              "//flutter/impeller/fixtures",
              "//flutter/fml",
-             "//flutter/fml/dart",
              "//flutter/runtime",
              "//flutter/runtime:libdart",
              "//flutter/testing",