Trace main thread commit in flow events.

cc/trees/thread_proxy.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/thread_proxy.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/auto_reset.h"
@@ skipping 849 matching lines @@
     return;
   }
 
   // Notify the impl thread that the main thread is ready to commit. This will
   // begin the commit process, which is blocking from the main thread's
   // point of view, but asynchronously performed on the impl thread,
   // coordinated by the Scheduler.
   {
     TRACE_EVENT0("cc", "ThreadProxy::BeginMainFrame::commit");
 
+    layer_tree_host()->trace_commit();
+
     DebugScopedSetMainThreadBlocked main_thread_blocked(this);
 
     // This CapturePostTasks should be destroyed before CommitComplete() is
     // called since that goes out to the embedder, and we want the embedder
     // to receive its callbacks before that.
     BlockingTaskRunner::CapturePostTasks blocked(
         blocking_main_thread_task_runner());
 
     CompletionEvent completion;
     Proxy::ImplThreadTaskRunner()->PostTask(
@@ skipping 545 matching lines @@
 
 void ThreadProxy::PostFrameTimingEvents(
     scoped_ptr<FrameTimingTracker::CompositeTimingSet> composite_events,
     scoped_ptr<FrameTimingTracker::MainFrameTimingSet> main_frame_events) {
   DCHECK(IsMainThread());
   layer_tree_host()->RecordFrameTimingEvents(composite_events.Pass(),
                                              main_frame_events.Pass());
 }
 
 }  // namespace cc