Made root translation layer the root when using pinch virtual viewport.

Source/core/frame/PinchViewport.h

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 51 matching lines @@
 // main FrameView, which corresponds to the outer viewport. The inner viewport is always contained
 // in the outer viewport and can pan within it.
 class PinchViewport FINAL : public GraphicsLayerClient, public ScrollableArea {
 public:
     explicit PinchViewport(FrameHost&);
     virtual ~PinchViewport();
 
     void attachToLayerTree(GraphicsLayer*, GraphicsLayerFactory*);
     GraphicsLayer* rootGraphicsLayer()
     {
+        return m_rootTransformLayer.get();
+    }
+    GraphicsLayer* containerLayer()
+    {
         return m_innerViewportContainerLayer.get();
     }
 
     // Sets the location of the inner viewport relative to the outer viewport. The
     // coordinates are in partial CSS pixels.
     void setLocation(const FloatPoint&);
     void move(const FloatPoint&);
 
     // Sets the size of the inner viewport when unscaled in CSS pixels.
     // This will be clamped to the size of the outer viewport (the main frame).
@@ skipping 52 matching lines @@
     virtual void notifyAnimationStarted(const GraphicsLayer*, double monotonicTime) OVERRIDE;
     virtual void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect& inClip) OVERRIDE;
     virtual String debugName(const GraphicsLayer*) OVERRIDE;
 
     void setupScrollbar(blink::WebScrollbar::Orientation);
     FloatPoint clampOffsetToBoundaries(const FloatPoint&);
 
     LocalFrame* mainFrame() const;
 
     FrameHost& m_frameHost;
+    OwnPtr<GraphicsLayer> m_rootTransformLayer;
     OwnPtr<GraphicsLayer> m_innerViewportContainerLayer;
     OwnPtr<GraphicsLayer> m_pageScaleLayer;
     OwnPtr<GraphicsLayer> m_innerViewportScrollLayer;
     OwnPtr<GraphicsLayer> m_overlayScrollbarHorizontal;
     OwnPtr<GraphicsLayer> m_overlayScrollbarVertical;
     OwnPtr<blink::WebScrollbarLayer> m_webOverlayScrollbarHorizontal;
     OwnPtr<blink::WebScrollbarLayer> m_webOverlayScrollbarVertical;
 
     // Offset of the pinch viewport from the main frame's origin, in CSS pixels.
     FloatPoint m_offset;
     float m_scale;
     IntSize m_size;
 };
 
 } // namespace WebCore
 
 #endif // PinchViewport_h