Adding a metric to track only the checkerboarding.

cc/debug/rendering_stats_instrumentation.h

 // Copyright 2013 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_DEBUG_RENDERING_STATS_INSTRUMENTATION_H_
 #define CC_DEBUG_RENDERING_STATS_INSTRUMENTATION_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/synchronization/lock.h"
 #include "cc/debug/rendering_stats.h"
@@ skipping 25 matching lines @@
     if (record_rendering_stats_ != record_rendering_stats)
       record_rendering_stats_ = record_rendering_stats;
   }
 
   base::TimeTicks StartRecording() const;
   base::TimeDelta EndRecording(base::TimeTicks start_time) const;
 
   void IncrementFrameCount(int64 count);
   void AddVisibleContentArea(int64 area);
   void AddApproximatedVisibleContentArea(int64 area);
+  void AddCheckerboardedVisibleContentArea(int64 area);
   void AddDrawDuration(base::TimeDelta draw_duration,
                        base::TimeDelta draw_duration_estimate);
   void AddBeginMainFrameToCommitDuration(
       base::TimeDelta begin_main_frame_to_commit_duration,
       base::TimeDelta begin_main_frame_to_commit_duration_estimate);
   void AddCommitToActivateDuration(
       base::TimeDelta commit_to_activate_duration,
       base::TimeDelta commit_to_activate_duration_estimate);
 
  protected:
   RenderingStatsInstrumentation();
 
  private:
   RenderingStats impl_thread_rendering_stats_;
   RenderingStats impl_thread_rendering_stats_accu_;
 
   bool record_rendering_stats_;
 
   base::Lock lock_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderingStatsInstrumentation);
 };
 
 }  // namespace cc
 
 #endif  // CC_DEBUG_RENDERING_STATS_INSTRUMENTATION_H_