GPU benchmarks should track the frequency of impl-thread vs. main-thread scrolls

cc/CCLayerTreeHostImpl.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 CCLayerTreeHostImpl_h
 #define CCLayerTreeHostImpl_h
 
 #include "base/basictypes.h"
 #include "base/time.h"
 #include "CCAnimationEvents.h"
@@ skipping 276 matching lines @@
 
     CCLayerSorter m_layerSorter;
 
     // List of visible layers for the most recently prepared frame. Used for
     // rendering and input event hit testing.
     CCLayerList m_renderSurfaceLayerList;
 
     OwnPtr<CCFrameRateCounter> m_fpsCounter;
     OwnPtr<CCDebugRectHistory> m_debugRectHistory;
 
+    size_t m_numImplThreadScrolls;
+    size_t m_numMainThreadScrolls;
+
     DISALLOW_COPY_AND_ASSIGN(CCLayerTreeHostImpl);
 };
 
 };
 
 #endif