Make sure the secondary vsync callback is called after the vsync callback (flutter/engine#31513)

engine/src/flutter/shell/common/fixtures/shell_test.dart

@@ -264,7 +264,7 @@ void canReceiveArgumentsWhenEngineSpawn(List<String> args) {
 }
 
 @pragma('vm:entry-point')
-void canScheduleFrameFromPlatform() {
+void onBeginFrameWithNotifyNativeMain() {
   PlatformDispatcher.instance.onBeginFrame = (Duration beginTime) {
     nativeOnBeginFrame(beginTime.inMicroseconds);
   };

engine/src/flutter/shell/common/shell_unittests.cc

@@ -1848,7 +1848,7 @@ TEST_F(ShellTest, CanScheduleFrameFromPlatform) {
   ASSERT_TRUE(shell->IsSetup());
 
   auto configuration = RunConfiguration::InferFromSettings(settings);
-  configuration.SetEntrypoint("canScheduleFrameFromPlatform");
+  configuration.SetEntrypoint("onBeginFrameWithNotifyNativeMain");
   RunEngine(shell.get(), std::move(configuration));
 
   // Wait for the application to attach the listener.
@@ -1861,6 +1861,50 @@ TEST_F(ShellTest, CanScheduleFrameFromPlatform) {
   DestroyShell(std::move(shell), std::move(task_runners));
 }
 
+TEST_F(ShellTest, SecondaryVsyncCallbackShouldBeCalledAfterVsyncCallback) {
+  bool is_on_begin_frame_called = false;
+  bool is_secondary_callback_called = false;
+  Settings settings = CreateSettingsForFixture();
+  TaskRunners task_runners = GetTaskRunnersForFixture();
+  fml::AutoResetWaitableEvent latch;
+  AddNativeCallback(
+      "NotifyNative",
+      CREATE_NATIVE_ENTRY([&](Dart_NativeArguments args) { latch.Signal(); }));
+  fml::CountDownLatch count_down_latch(2);
+  AddNativeCallback("NativeOnBeginFrame",
+                    CREATE_NATIVE_ENTRY([&](Dart_NativeArguments args) {
+                      EXPECT_FALSE(is_on_begin_frame_called);
+                      EXPECT_FALSE(is_secondary_callback_called);
+                      is_on_begin_frame_called = true;
+                      count_down_latch.CountDown();
+                    }));
+  std::unique_ptr<Shell> shell =
+      CreateShell(std::move(settings), std::move(task_runners));
+  ASSERT_TRUE(shell->IsSetup());
+
+  auto configuration = RunConfiguration::InferFromSettings(settings);
+  configuration.SetEntrypoint("onBeginFrameWithNotifyNativeMain");
+  RunEngine(shell.get(), std::move(configuration));
+
+  // Wait for the application to attach the listener.
+  latch.Wait();
+
+  fml::TaskRunner::RunNowOrPostTask(
+      shell->GetTaskRunners().GetUITaskRunner(), [&]() {
+        shell->GetEngine()->ScheduleSecondaryVsyncCallback(0, [&]() {
+          EXPECT_TRUE(is_on_begin_frame_called);
+          EXPECT_FALSE(is_secondary_callback_called);
+          is_secondary_callback_called = true;
+          count_down_latch.CountDown();
+        });
+        shell->GetEngine()->ScheduleFrame();
+      });
+  count_down_latch.Wait();
+  EXPECT_TRUE(is_on_begin_frame_called);
+  EXPECT_TRUE(is_secondary_callback_called);
+  DestroyShell(std::move(shell), std::move(task_runners));
+}
+
 static void LogSkData(sk_sp<SkData> data, const char* title) {
   FML_LOG(ERROR) << "---------- " << title;
   std::ostringstream ostr;

engine/src/flutter/shell/common/vsync_waiter.cc

@@ -154,8 +154,7 @@ void VsyncWaiter::FireCallback(fml::TimePoint frame_start_time,
   }
 
   for (auto& secondary_callback : secondary_callbacks) {
-    task_runners_.GetUITaskRunner()->PostTaskForTime(
-        std::move(secondary_callback), frame_start_time);
+    task_runners_.GetUITaskRunner()->PostTask(std::move(secondary_callback));
   }
 }