cc: Record UMA for swap to swap ack latency.

cc/scheduler/compositor_timing_history.h

 // Copyright 2014 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_SCHEDULER_COMPOSITOR_TIMING_HISTORY_H_
 #define CC_SCHEDULER_COMPOSITOR_TIMING_HISTORY_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/rolling_time_delta_history.h"
 
@@ skipping 43 matching lines @@
   void BeginMainFrameStarted(base::TimeTicks main_thread_start_time);
   void BeginMainFrameAborted();
   void DidCommit();
   void WillPrepareTiles();
   void DidPrepareTiles();
   void ReadyToActivate();
   void WillActivate();
   void DidActivate();
   void WillDraw();
   void DidDraw();
+  void DidSwapBuffers();
+  void DidSwapBuffersComplete();
+  void DidSwapBuffersReset();
 
  protected:
   static scoped_ptr<UMAReporter> CreateUMAReporter(UMACategory category);
   virtual base::TimeTicks Now() const;
 
   bool enabled_;
 
   RollingTimeDeltaHistory begin_main_frame_sent_to_commit_duration_history_;
   RollingTimeDeltaHistory begin_main_frame_queue_duration_critical_history_;
   RollingTimeDeltaHistory begin_main_frame_queue_duration_not_critical_history_;
   RollingTimeDeltaHistory begin_main_frame_start_to_commit_duration_history_;
   RollingTimeDeltaHistory commit_to_ready_to_activate_duration_history_;
   RollingTimeDeltaHistory prepare_tiles_duration_history_;
   RollingTimeDeltaHistory activate_duration_history_;
   RollingTimeDeltaHistory draw_duration_history_;
 
   bool begin_main_frame_on_critical_path_;
   base::TimeTicks begin_main_frame_sent_time_;
   base::TimeTicks begin_main_frame_start_time_;
   base::TimeTicks commit_time_;
   base::TimeTicks start_prepare_tiles_time_;
   base::TimeTicks start_activate_time_;
   base::TimeTicks start_draw_time_;
+  base::TimeTicks swap_start_time_;

[tdresser, 2015/11/06 13:00:34]

start_swap_time_, for consistency.

[mithro-old, 2015/11/07 04:13:15]

Won't this fail if we have a max_pending_swaps > 1?

 
   scoped_ptr<UMAReporter> uma_reporter_;
   RenderingStatsInstrumentation* rendering_stats_instrumentation_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CompositorTimingHistory);
 };
 
 }  // namespace cc
 
 #endif  // CC_SCHEDULER_COMPOSITOR_TIMING_HISTORY_H_