cc: Add MainAndImplFrameTimeDelta UMA.

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/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/rolling_time_delta_history.h"
@@ skipping 46 matching lines @@
   void WillBeginMainFrame(bool on_critical_path);
   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(bool used_new_active_tree);
+  void DidDraw(bool used_new_active_tree,
+               bool main_thread_missed_last_deadline);

[tdresser, 2016/02/10 17:15:20]

Would it make sense to record how many deadlines the main thread missed?

[Sami, 2016/02/10 17:28:54]

Do you mean the lateness in milliseconds? I guess with this patch an overrun of
1ms and 100ms would be in the same bucket. I feel like those numbers might be
derivable from the BeginMainFrame timing UMAs, but I don't have proof :)

   void DidSwapBuffers();
   void DidSwapBuffersComplete();
   void DidSwapBuffersReset();
 
  protected:
   void DidBeginMainFrame();
 
   void SetBeginMainFrameNeededContinuously(bool active);
   void SetBeginMainFrameCommittingContinuously(bool active);
   void SetCompositorDrawingContinuously(bool active);
@@ skipping 33 matching lines @@
   scoped_ptr<UMAReporter> uma_reporter_;
   RenderingStatsInstrumentation* rendering_stats_instrumentation_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CompositorTimingHistory);
 };
 
 }  // namespace cc
 
 #endif  // CC_SCHEDULER_COMPOSITOR_TIMING_HISTORY_H_