Add destruction test

shell/platform/embedder/fixtures/main.dart

@@ -498,6 +498,38 @@ void can_composite_platform_views_with_platform_layer_on_bottom() {
   PlatformDispatcher.instance.scheduleFrame();
 }
 
+@pragma('vm:external-name', 'SignalBeginFrame')
+external void signalBeginFrame();
+
+@pragma('vm:entry-point')
+void texture_destruction_callback_called_without_custom_compositor() async {
+  PlatformDispatcher.instance.onBeginFrame = (Duration duration) {
+    Color red = Color.fromARGB(127, 255, 0, 0);
+    Size size = Size(50.0, 150.0);
+    SceneBuilder builder = SceneBuilder();
+    builder.pushOffset(0.0, 0.0);
+    builder.addPicture(
+        Offset(10.0, 10.0), CreateColoredBox(red, size)); // red - flutter
+    builder.pop();
+    PlatformDispatcher.instance.views.first.render(builder.build());
+  };
+
+  // Schedule first frame.
+  final Completer firstFrame = Completer();
+  PlatformDispatcher.instance.onDrawFrame = () { firstFrame.complete(); };
+  PlatformDispatcher.instance.scheduleFrame();
+  await firstFrame.future;
+
+  // Schedule second frame to trigger disposal of first surface.
+  final Completer secondFrame = Completer();
+  PlatformDispatcher.instance.onDrawFrame = () { secondFrame.complete(); };
+  PlatformDispatcher.instance.scheduleFrame();
+  await secondFrame.future;
+
+  signalNativeTest();
+}
+
+
 @pragma('vm:entry-point')
 void can_render_scene_without_custom_compositor() {
   PlatformDispatcher.instance.onBeginFrame = (Duration duration) {

shell/platform/embedder/tests/embedder_test_context_metal.cc

@@ -71,10 +71,22 @@ bool EmbedderTestContextMetal::PopulateExternalTexture(
   }
 }
 
+TestMetalContext::TextureInfo EmbedderTestContextMetal::GetTextureInfo() {
+  return metal_surface_->GetTextureInfo();
+}
+
+void EmbedderTestContextMetal::SetNextDrawableCallback(
+    NextDrawableCallback next_drawable_callback) {
+  next_drawable_callback_ = next_drawable_callback;
+}
+
 FlutterMetalTexture EmbedderTestContextMetal::GetNextDrawable(
     const FlutterFrameInfo* frame_info) {
-  auto texture_info = metal_surface_->GetTextureInfo();
+  if (next_drawable_callback_ != nullptr) {
+    return next_drawable_callback_(frame_info);
+  }
 
+  auto texture_info = metal_surface_->GetTextureInfo();
   FlutterMetalTexture texture;
   texture.struct_size = sizeof(FlutterMetalTexture);
   texture.texture_id = texture_info.texture_id;

shell/platform/embedder/tests/embedder_test_context_metal.h

@@ -20,6 +20,9 @@ class EmbedderTestContextMetal : public EmbedderTestContext {
                          size_t h,
                          FlutterMetalExternalTexture* output)>;
 
+  using NextDrawableCallback =
+      std::function<FlutterMetalTexture(const FlutterFrameInfo* frame_info)>;
+
   explicit EmbedderTestContextMetal(std::string assets_path = "");
 
   ~EmbedderTestContextMetal() override;
@@ -45,6 +48,12 @@ class EmbedderTestContextMetal : public EmbedderTestContext {
 
   TestMetalContext* GetTestMetalContext();
 
+  // Returns the TextureInfo for the test Metal surface.
+  TestMetalContext::TextureInfo GetTextureInfo();
+
+  // Override the default handling for GetNextDrawable.
+  void SetNextDrawableCallback(NextDrawableCallback next_drawable_callback);
+
   FlutterMetalTexture GetNextDrawable(const FlutterFrameInfo* frame_info);
 
  private:
@@ -56,6 +65,7 @@ class EmbedderTestContextMetal : public EmbedderTestContext {
   std::unique_ptr<TestMetalContext> metal_context_;
   std::unique_ptr<TestMetalSurface> metal_surface_;
   size_t present_count_ = 0;
+  NextDrawableCallback next_drawable_callback_ = nullptr;
 
   void SetupSurface(SkISize surface_size) override;
 

shell/platform/embedder/tests/embedder_unittests_metal.mm

@@ -227,6 +227,52 @@ GrBackendTexture backend_texture(texture_size.width(), texture_size.height(), Gr
   ASSERT_TRUE(ImageMatchesFixture("scene_without_custom_compositor.png", rendered_scene));
 }
 
+TEST_F(EmbedderTest, TextureDestructionCallbackCalledWithoutCustomCompositorMetal) {
+  EmbedderTestContextMetal& context = reinterpret_cast<EmbedderTestContextMetal&>(
+      GetEmbedderContext(EmbedderTestContextType::kMetalContext));
+  EmbedderConfigBuilder builder(context);
+  builder.SetMetalRendererConfig(SkISize::Make(800, 600));
+  builder.SetDartEntrypoint("texture_destruction_callback_called_without_custom_compositor");
+
+  struct CollectContext {
+    bool collected = false;
+  };
+
+  auto collect_context = std::make_unique<CollectContext>();
+  context.SetNextDrawableCallback([&context, &collect_context](const FlutterFrameInfo* frame_info) {
+    auto texture_info = context.GetTextureInfo();
+    FlutterMetalTexture texture;
+    texture.struct_size = sizeof(FlutterMetalTexture);
+    texture.texture_id = texture_info.texture_id;
+    texture.texture = reinterpret_cast<FlutterMetalTextureHandle>(texture_info.texture);
+    texture.user_data = collect_context.get();
+    texture.destruction_callback = [](void* user_data) {
+      CollectContext* callback_collect_context = reinterpret_cast<CollectContext*>(user_data);
+      callback_collect_context->collected = true;
+    };
+    return texture;
+  });
+
+  fml::AutoResetWaitableEvent latch;
+  context.AddNativeCallback(
+      "SignalNativeTest",
+      CREATE_NATIVE_ENTRY([&latch](Dart_NativeArguments args) { latch.Signal(); }));
+
+  auto engine = builder.LaunchEngine();
+
+  // Send a window metrics events so frames may be scheduled.
+  FlutterWindowMetricsEvent event = {};
+  event.struct_size = sizeof(event);
+  event.width = 800;
+  event.height = 600;
+  event.pixel_ratio = 1.0;
+  ASSERT_EQ(FlutterEngineSendWindowMetricsEvent(engine.get(), &event), kSuccess);
+  ASSERT_TRUE(engine.is_valid());
+
+  latch.Wait();
+  EXPECT_TRUE(collect_context->collected);
+}
+
 TEST_F(EmbedderTest, CompositorMustBeAbleToRenderKnownSceneMetal) {
   auto& context = GetEmbedderContext(EmbedderTestContextType::kMetalContext);