cc: Send all begin frames using a PostTask.

cc/test/pixel_test_delegating_output_surface.cc

Index: cc/test/pixel_test_delegating_output_surface.cc
diff --git a/cc/test/pixel_test_delegating_output_surface.cc b/cc/test/pixel_test_delegating_output_surface.cc
index cc63498853a3a2064c18abbf332f94e9137ac953..d4212fc1bdea398fc2c0eb21eff488fd4afabc18 100644
--- a/cc/test/pixel_test_delegating_output_surface.cc
+++ b/cc/test/pixel_test_delegating_output_surface.cc
@@ -88,8 +88,7 @@ bool PixelTestDelegatingOutputSurface::BindToClient(
   std::unique_ptr<SyntheticBeginFrameSource> begin_frame_source;
   std::unique_ptr<DisplayScheduler> scheduler;
   if (!synchronous_composite_) {
-    begin_frame_source.reset(new DelayBasedBeginFrameSource(
-        base::MakeUnique<DelayBasedTimeSource>(task_runner)));
+    begin_frame_source.reset(new DelayBasedBeginFrameSource(task_runner));
     scheduler.reset(new DisplayScheduler(
         begin_frame_source.get(), task_runner,
         output_surface->capabilities().max_frames_pending));