Adding a metric to track only the checkerboarding.

cc/debug/rendering_stats.h

 // Copyright 2012 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_H_
 #define CC_DEBUG_RENDERING_STATS_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 26 matching lines @@
 
   RenderingStats();
   ~RenderingStats();
 
   // Note: when adding new members, please remember to update Add in
   // rendering_stats.cc.
 
   int64 frame_count;
   int64 visible_content_area;
   int64 approximated_visible_content_area;
+  int64 checkerboarded_visible_content_area;
 
   TimeDeltaList draw_duration;
   TimeDeltaList draw_duration_estimate;
   TimeDeltaList begin_main_frame_to_commit_duration;
   TimeDeltaList begin_main_frame_to_commit_duration_estimate;
   TimeDeltaList commit_to_activate_duration;
   TimeDeltaList commit_to_activate_duration_estimate;
 
   scoped_refptr<base::trace_event::ConvertableToTraceFormat> AsTraceableData()
       const;
   void Add(const RenderingStats& other);
 };
 
 }  // namespace cc
 
 #endif  // CC_DEBUG_RENDERING_STATS_H_