Implement pinch-zoom scaling for main-frame scrollbars and pinch-zoom overlay scrollbars.

cc/scrollbar_layer.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_SCROLLBAR_LAYER_H_
 #define CC_SCROLLBAR_LAYER_H_
 
 #include "cc/caching_bitmap_content_layer_updater.h"
 #include "cc/cc_export.h"
 #include "cc/contents_scaling_layer.h"
 #include <public/WebScrollbar.h>
 #include <public/WebScrollbarThemeGeometry.h>
 #include <public/WebScrollbarThemePainter.h>
 
 namespace cc {
 
 class ResourceUpdateQueue;
 class Scrollbar;
-class ScrollbarThemeComposite;
 
 class CC_EXPORT ScrollbarLayer : public ContentsScalingLayer {
 public:
     virtual scoped_ptr<LayerImpl> createLayerImpl(LayerTreeImpl* treeImpl) OVERRIDE;
 
     static scoped_refptr<ScrollbarLayer> create(scoped_ptr<WebKit::WebScrollbar>, WebKit::WebScrollbarThemePainter, scoped_ptr<WebKit::WebScrollbarThemeGeometry>, int scrollLayerId);
 
     int scrollLayerId() const { return m_scrollLayerId; }
     void setScrollLayerId(int id);
 
@@ skipping 30 matching lines @@
     scoped_refptr<CachingBitmapContentLayerUpdater> m_thumbUpdater;
 
     // All the parts of the scrollbar except the thumb
     scoped_ptr<LayerUpdater::Resource> m_backTrack;
     scoped_ptr<LayerUpdater::Resource> m_foreTrack;
     scoped_ptr<LayerUpdater::Resource> m_thumb;
 };
 
 }
 #endif  // CC_SCROLLBAR_LAYER_H_