Add graphics layers for pinch virtual viewport.

Source/core/rendering/RenderLayerCompositor.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 310 matching lines @@
     bool m_compositing;
     bool m_compositingLayersNeedRebuild;
     bool m_forceCompositingMode;
     bool m_inPostLayoutUpdate; // true when it's OK to trust layout information (e.g. layer sizes and positions)
 
     bool m_isTrackingRepaints; // Used for testing.
     
     RootLayerAttachment m_rootLayerAttachment;
 
     // Enclosing clipping layer for iframe content
-    OwnPtr<GraphicsLayer> m_clipLayer;
-    OwnPtr<GraphicsLayer> m_scrollLayer;
+    OwnPtr<GraphicsLayer> m_innerViewportClipLayer;
+    OwnPtr<GraphicsLayer> m_innerViewportScrollLayer;
 
     HashSet<RenderLayer*> m_viewportConstrainedLayers;
     HashSet<RenderLayer*> m_viewportConstrainedLayersNeedingUpdate;
 
     // Enclosing layer for overflow controls and the clipping layer
     OwnPtr<GraphicsLayer> m_overflowControlsHostLayer;
 
+    // Layers for pinch virtual viewport layers
+    OwnPtr<GraphicsLayer> m_pageScaleLayer;
+    OwnPtr<GraphicsLayer> m_outerViewportClipLayer;
+    OwnPtr<GraphicsLayer> m_outerViewportScrollLayer;
+
     // Layers for overflow controls
     OwnPtr<GraphicsLayer> m_layerForHorizontalScrollbar;
     OwnPtr<GraphicsLayer> m_layerForVerticalScrollbar;
     OwnPtr<GraphicsLayer> m_layerForScrollCorner;
 #if ENABLE(RUBBER_BANDING)
     OwnPtr<GraphicsLayer> m_layerForOverhangAreas;
     OwnPtr<GraphicsLayer> m_contentShadowLayer;
     OwnPtr<GraphicsLayer> m_layerForTopOverhangArea;
     OwnPtr<GraphicsLayer> m_layerForBottomOverhangArea;
 #endif
 
 #if !LOG_DISABLED
     int m_rootLayerUpdateCount;
     int m_obligateCompositedLayerCount; // count of layer that have to be composited.
     int m_secondaryCompositedLayerCount; // count of layers that have to be composited because of stacking or overlap.
     double m_obligatoryBackingStoreBytes;
     double m_secondaryBackingStoreBytes;
 #endif
 };
 
 
 } // namespace WebCore
 
 #endif // RenderLayerCompositor_h