Comments

shell/platform/embedder/embedder.cc

@@ -2143,7 +2143,7 @@ FlutterEngineResult FlutterEngineSendWindowMetricsEvent(
   if (engine == nullptr || flutter_metrics == nullptr) {
     return LOG_EMBEDDER_ERROR(kInvalidArguments, "Engine handle was invalid.");
   }
-  int64_t view_id =
+  FlutterViewId view_id =
       SAFE_ACCESS(flutter_metrics, view_id, kFlutterImplicitViewId);
 
   flutter::ViewportMetrics metrics;

shell/platform/embedder/tests/embedder_unittests.cc

@@ -2772,7 +2772,7 @@ TEST_F(EmbedderTest, WindowMetricsEventDefaultsToImplicitView) {
   builder.SetSoftwareRendererConfig();
   builder.SetDartEntrypoint("window_metrics_event_view_id");
 
-  fml::AutoResetWaitableEvent ready_latch, count_latch, message_latch;
+  fml::AutoResetWaitableEvent ready_latch, message_latch;
   context.AddNativeCallback(
       "SignalNativeTest",
       CREATE_NATIVE_ENTRY(
@@ -2792,7 +2792,9 @@ TEST_F(EmbedderTest, WindowMetricsEventDefaultsToImplicitView) {
   ready_latch.Wait();
 
   FlutterWindowMetricsEvent event = {};
-  event.struct_size = sizeof(FlutterWindowMetricsEvent);
+  // Simulate an event that comes from an old version of embedder.h that doesn't
+  // have the view_id field.
+  event.struct_size = offsetof(FlutterWindowMetricsEvent, view_id);
   event.width = 200;
   event.height = 300;
   event.pixel_ratio = 1.5;
@@ -2805,6 +2807,62 @@ TEST_F(EmbedderTest, WindowMetricsEventDefaultsToImplicitView) {
   message_latch.Wait();
 }
 
+TEST_F(EmbedderTest, IgnoresWindowMetricsEventForUnknownView) {
+  auto& context = GetEmbedderContext(EmbedderTestContextType::kSoftwareContext);
+  EmbedderConfigBuilder builder(context);
+  builder.SetSoftwareRendererConfig();
+  builder.SetDartEntrypoint("window_metrics_event_view_id");
+
+  fml::AutoResetWaitableEvent ready_latch, message_latch;
+  context.AddNativeCallback(
+      "SignalNativeTest",
+      CREATE_NATIVE_ENTRY(
+          [&ready_latch](Dart_NativeArguments args) { ready_latch.Signal(); }));
+
+  context.AddNativeCallback(
+      "SignalNativeMessage",
+      CREATE_NATIVE_ENTRY([&message_latch](Dart_NativeArguments args) {
+        auto message = tonic::DartConverter<std::string>::FromDart(
+            Dart_GetNativeArgument(args, 0));
+        // Message latch should only be signaled once as the bad
+        // view metric should be dropped by the engine.
+        ASSERT_FALSE(message_latch.IsSignaledForTest());
+        ASSERT_EQ("Changed: [0]", message);
+        message_latch.Signal();
+      }));
+
+  auto engine = builder.LaunchEngine();
+  ASSERT_TRUE(engine.is_valid());
+
+  ready_latch.Wait();
+
+  // Send a window metric for a nonexistent view, which should be dropped by the
+  // engine.
+  FlutterWindowMetricsEvent bad_event = {};
+  bad_event.struct_size = sizeof(FlutterWindowMetricsEvent);
+  bad_event.width = 200;
+  bad_event.height = 300;
+  bad_event.pixel_ratio = 1.5;
+  bad_event.view_id = 100;
+
+  FlutterEngineResult result =
+      FlutterEngineSendWindowMetricsEvent(engine.get(), &bad_event);
+  ASSERT_EQ(result, kSuccess);
+
+  // Send a window metric for a valid view. The engine notifies the Dart app.
+  FlutterWindowMetricsEvent event = {};
+  event.struct_size = sizeof(FlutterWindowMetricsEvent);
+  event.width = 200;
+  event.height = 300;
+  event.pixel_ratio = 1.5;
+  event.view_id = 0;
+
+  result = FlutterEngineSendWindowMetricsEvent(engine.get(), &event);
+  ASSERT_EQ(result, kSuccess);
+
+  message_latch.Wait();
+}
+
 TEST_F(EmbedderTest, RegisterChannelListener) {
   auto& context = GetEmbedderContext(EmbedderTestContextType::kSoftwareContext);
 

shell/platform/linux/fl_engine.cc

@@ -763,7 +763,7 @@ void fl_engine_send_window_metrics_event(FlEngine* self,
   // TODO(dkwingsmt): Assign the correct view ID once the Linux embedder
   // supports multiple views.
   // https://github.com/flutter/flutter/issues/138178
-  fl_event.view_id = flutter::kFlutterImplicitViewId;
+  event.view_id = flutter::kFlutterImplicitViewId;
   self->embedder_api.SendWindowMetricsEvent(self->engine, &event);
 }
 

shell/platform/windows/flutter_windows_view.cc

@@ -352,7 +352,7 @@ void FlutterWindowsView::SendWindowMetrics(size_t width,
   event.width = width;
   event.height = height;
   event.pixel_ratio = dpiScale;
-  event.view_id = view_id();
+  event.view_id = view_id_;
   engine_->SendWindowMetricsEvent(event);
 }
 
@@ -589,7 +589,7 @@ void FlutterWindowsView::SendPointerEventWithData(
   event.device_kind = state->device_kind;
   event.device = state->pointer_id;
   event.buttons = state->buttons;
-  event.view_id = view_id();
+  event.view_id = view_id_;
 
   // Set metadata that's always the same regardless of the event.
   event.struct_size = sizeof(event);