Support high DPI scrollbar on top level web frame.

cc/CCLayerImpl.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 CCLayerImpl_h
 #define CCLayerImpl_h
 
 #include "CCInputHandler.h"
 #include "CCLayerAnimationController.h"
 #include "CCRenderSurface.h"
@@ skipping 239 matching lines @@
     void setHorizontalScrollbarLayer(CCScrollbarLayerImpl*);
 
     CCScrollbarLayerImpl* verticalScrollbarLayer() const;
     void setVerticalScrollbarLayer(CCScrollbarLayerImpl*);
 
 protected:
     explicit CCLayerImpl(int);
 
     void appendDebugBorderQuad(CCQuadSink&, const CCSharedQuadState*, CCAppendQuadsData&) const;
 
+    IntRect layerRectToContentRect(const WebKit::WebRect& layerRect);
+
     virtual void dumpLayerProperties(std::string*, int indent) const;
     static std::string indentString(int indent);
 
 private:
     void setParent(CCLayerImpl* parent) { m_parent = parent; }
     friend class TreeSynchronizer;
     void clearChildList(); // Warning: This does not preserve tree structure invariants and so is only exposed to the tree synchronizer.
 
     void noteLayerPropertyChangedForSubtree();
 
@@ skipping 113 matching lines @@
 
     // Manages scrollbars for this layer
     OwnPtr<CCScrollbarAnimationController> m_scrollbarAnimationController;
 };
 
 void sortLayers(Vector<CCLayerImpl*>::iterator first, Vector<CCLayerImpl*>::iterator end, CCLayerSorter*);
 
 }
 
 #endif // CCLayerImpl_h