cc: Get rid of PostSwapBuffersComplete.

cc/test/fake_compositor_frame_sink.cc

Index: cc/test/fake_compositor_frame_sink.cc
diff --git a/cc/test/fake_compositor_frame_sink.cc b/cc/test/fake_compositor_frame_sink.cc
index 91775d3869112cb07d07dcd0288c3af2123ff052..73336bc59517f94a480258e65e41686a9e4e8a07 100644
--- a/cc/test/fake_compositor_frame_sink.cc
+++ b/cc/test/fake_compositor_frame_sink.cc
@@ -5,7 +5,7 @@
 #include "cc/test/fake_compositor_frame_sink.h"
 
 #include "base/bind.h"
-#include "base/message_loop/message_loop.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "cc/output/compositor_frame_sink_client.h"
 #include "cc/resources/returned_resource.h"
 #include "cc/test/begin_frame_args_test.h"
@@ -17,7 +17,8 @@ FakeCompositorFrameSink::FakeCompositorFrameSink(
     scoped_refptr<ContextProvider> context_provider,
     scoped_refptr<ContextProvider> worker_context_provider)
     : CompositorFrameSink(std::move(context_provider),
-                          std::move(worker_context_provider)) {}
+                          std::move(worker_context_provider)),
+      weak_ptr_factory_(this) {}
 
 FakeCompositorFrameSink::~FakeCompositorFrameSink() = default;
 
@@ -45,7 +46,13 @@ void FakeCompositorFrameSink::SwapBuffers(CompositorFrame frame) {
     }
   }
 
-  PostSwapBuffersComplete();
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(&FakeCompositorFrameSink::SwapBuffersAck,
+                            weak_ptr_factory_.GetWeakPtr()));
+}
+
+void FakeCompositorFrameSink::SwapBuffersAck() {
+  client_->DidSwapBuffersComplete();
 }
 
 bool FakeCompositorFrameSink::BindToClient(CompositorFrameSinkClient* client) {