cc: Start commit early and block on tree activation

cc/trees/thread_proxy.h

 // 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.
 
 #ifndef CC_TREES_THREAD_PROXY_H_
 #define CC_TREES_THREAD_PROXY_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 210 matching lines @@
   scoped_ptr<LayerTreeHostImpl> layer_tree_host_impl_;
 
   scoped_ptr<Scheduler> scheduler_on_impl_thread_;
   bool frame_did_draw_;
 
   // Set when the main thread is waiting on a
   // ScheduledActionSendBeginFrameToMainThread to be issued.
   CompletionEvent*
       begin_frame_sent_to_main_thread_completion_event_on_impl_thread_;
 
+  // Set when there is a pending tree on a commit.
+  base::Closure deferred_start_commit_on_impl_thread_;
+
   // Set when the main thread is waiting on a readback.
   ReadbackRequest* readback_request_on_impl_thread_;
 
   // Set when the main thread is waiting on a commit to complete.
   CompletionEvent* commit_completion_event_on_impl_thread_;
 
   // Set when the main thread is waiting on a pending tree activation.
   CompletionEvent* completion_event_for_commit_held_on_tree_activation_;
 
   // Set when the main thread is waiting on layers to be drawn.
@@ skipping 30 matching lines @@
   // activation_duration_history_.
   base::TimeTicks begin_frame_sent_to_main_thread_time_;
   base::TimeTicks commit_complete_time_;
 
   DISALLOW_COPY_AND_ASSIGN(ThreadProxy);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_THREAD_PROXY_H_