Add synchronous |PostTask| function.

Author: 0xZOne

fml/task_runner.cc

@@ -13,6 +13,7 @@
 #include "flutter/fml/message_loop.h"
 #include "flutter/fml/message_loop_impl.h"
 #include "flutter/fml/message_loop_task_queues.h"
+#include "flutter/fml/synchronization/waitable_event.h"
 
 namespace fml {
 
@@ -64,9 +65,19 @@ void TaskRunner::RunNowOrPostTask(fml::RefPtr<fml::TaskRunner> runner,
   }
 }
 
-void TaskRunner::RunNowOrPostSyncTask(fml::RefPtr<fml::TaskRunner> runner,
+void TaskRunner::RunNowOrPostTaskSync(fml::RefPtr<fml::TaskRunner> runner,
                                       const fml::closure& task) {
+  FML_DCHECK(runner);
   std::scoped_lock lock(g_thread_merging_lock);
-  RunNowOrPostTask(runner, task);
+  if (runner->RunsTasksOnCurrentThread()) {
+    task();
+  } else {
+    fml::AutoResetWaitableEvent latch;
+    runner->PostTask([&] {
+      task();
+      latch.Signal();
+    });
+    latch.Wait();
+  }
 }
 }  // namespace fml

fml/task_runner.h

@@ -66,9 +66,9 @@ class TaskRunner : public fml::RefCountedThreadSafe<TaskRunner>,
   static void RunNowOrPostTask(fml::RefPtr<fml::TaskRunner> runner,
                                const fml::closure& task);
 
-  /// Similar to |RunNowOrPostTask|, but it needs to synchronize with thread
-  /// merging operation.
-  static void RunNowOrPostSyncTask(fml::RefPtr<fml::TaskRunner> runner,
+  /// Similar to |RunNowOrPostTask|, but it needs to mutex with thread
+  /// merging operation and post the \p tast synchronously.
+  static void RunNowOrPostTaskSync(fml::RefPtr<fml::TaskRunner> runner,
                                    const fml::closure& task);
 
  protected:

shell/common/platform_view.cc

@@ -62,16 +62,14 @@ void PlatformView::NotifyCreated() {
   // Using the weak pointer is illegal. But, we are going to introduce a latch
   // so that the platform view is not collected till the surface is obtained.
   auto* platform_view = this;
-  fml::ManualResetWaitableEvent latch;
-  fml::TaskRunner::RunNowOrPostSyncTask(
-      task_runners_.GetRasterTaskRunner(), [platform_view, &surface, &latch]() {
+  fml::TaskRunner::RunNowOrPostTaskSync(
+      task_runners_.GetRasterTaskRunner(), [platform_view, &surface]() {
         surface = platform_view->CreateRenderingSurface();
         if (surface && !surface->IsValid()) {
           surface.reset();
         }
-        latch.Signal();
       });
-  latch.Wait();
+
   if (!surface) {
     FML_LOG(ERROR) << "Failed to create platform view rendering surface";
     return;

shell/platform/android/platform_view_android.cc

@@ -97,15 +97,12 @@ void PlatformViewAndroid::NotifyCreated(
   if (android_surface_) {
     InstallFirstFrameCallback();
 
-    fml::AutoResetWaitableEvent latch;
-    fml::TaskRunner::RunNowOrPostSyncTask(
+    fml::TaskRunner::RunNowOrPostTaskSync(
         task_runners_.GetRasterTaskRunner(),
-        [&latch, surface = android_surface_.get(),
+        [surface = android_surface_.get(),
          native_window = std::move(native_window)]() {
           surface->SetNativeWindow(native_window);
-          latch.Signal();
         });
-    latch.Wait();
   }
 
   PlatformView::NotifyCreated();
@@ -114,46 +111,37 @@ void PlatformViewAndroid::NotifyCreated(
 void PlatformViewAndroid::NotifySurfaceWindowChanged(
     fml::RefPtr<AndroidNativeWindow> native_window) {
   if (android_surface_) {
-    fml::AutoResetWaitableEvent latch;
-    fml::TaskRunner::RunNowOrPostSyncTask(
+    fml::TaskRunner::RunNowOrPostTaskSync(
         task_runners_.GetRasterTaskRunner(),
-        [&latch, surface = android_surface_.get(),
+        [surface = android_surface_.get(),
          native_window = std::move(native_window)]() {
           surface->TeardownOnScreenContext();
           surface->SetNativeWindow(native_window);
-          latch.Signal();
         });
-    latch.Wait();
   }
 }
 
 void PlatformViewAndroid::NotifyDestroyed() {
   PlatformView::NotifyDestroyed();
 
   if (android_surface_) {
-    fml::AutoResetWaitableEvent latch;
-    fml::TaskRunner::RunNowOrPostSyncTask(
-        task_runners_.GetRasterTaskRunner(),
-        [&latch, surface = android_surface_.get()]() {
-          surface->TeardownOnScreenContext();
-          latch.Signal();
-        });
-    latch.Wait();
+    fml::TaskRunner::RunNowOrPostTaskSync(task_runners_.GetRasterTaskRunner(),
+                                          [surface = android_surface_.get()]() {
+                                            surface->TeardownOnScreenContext();
+                                          });
   }
 }
 
 void PlatformViewAndroid::NotifyChanged(const SkISize& size) {
   if (!android_surface_) {
     return;
   }
-  fml::AutoResetWaitableEvent latch;
-  fml::TaskRunner::RunNowOrPostSyncTask(
-      task_runners_.GetRasterTaskRunner(),  //
-      [&latch, surface = android_surface_.get(), size]() {
+
+  fml::TaskRunner::RunNowOrPostTaskSync(
+      task_runners_.GetRasterTaskRunner(),
+      [surface = android_surface_.get(), size]() {
         surface->OnScreenSurfaceResize(size);
-        latch.Signal();
       });
-  latch.Wait();
 }
 
 void PlatformViewAndroid::DispatchPlatformMessage(JNIEnv* env,