Pass accurate contentsScale to LayerImpl.

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 ScrollbarLayerChromium_h
 #define ScrollbarLayerChromium_h
 
-#include "caching_bitmap_content_layer_updater.h"
-#include "cc/layer.h"
+#include "cc/caching_bitmap_content_layer_updater.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 ScrollbarLayer : public Layer {
+class ScrollbarLayer : public ContentsScalingLayer {
 public:
     virtual scoped_ptr<LayerImpl> createLayerImpl() OVERRIDE;
 
     static scoped_refptr<ScrollbarLayer> create(scoped_ptr<WebKit::WebScrollbar>, WebKit::WebScrollbarThemePainter, scoped_ptr<WebKit::WebScrollbarThemeGeometry>, int scrollLayerId);
 
     // Layer interface
-    virtual bool needsContentsScale() const OVERRIDE;
-    virtual IntSize contentBounds() const OVERRIDE;
     virtual void setTexturePriorities(const PriorityCalculator&) OVERRIDE;
     virtual void update(ResourceUpdateQueue&, const OcclusionTracker*, RenderingStats&) OVERRIDE;
     virtual void setLayerTreeHost(LayerTreeHost*) OVERRIDE;
     virtual void pushPropertiesTo(LayerImpl*) OVERRIDE;
 
     int scrollLayerId() const { return m_scrollLayerId; }
     void setScrollLayerId(int id) { m_scrollLayerId = id; }
 
     virtual ScrollbarLayer* toScrollbarLayer() OVERRIDE;
 
 protected:
     ScrollbarLayer(scoped_ptr<WebKit::WebScrollbar>, WebKit::WebScrollbarThemePainter, scoped_ptr<WebKit::WebScrollbarThemeGeometry>, int scrollLayerId);
     virtual ~ScrollbarLayer();
 
 private:
     void updatePart(CachingBitmapContentLayerUpdater*, LayerUpdater::Resource*, const IntRect&, ResourceUpdateQueue&, RenderingStats&);
     void createUpdaterIfNeeded();
+    IntRect scrollbarLayerRectToContentRect(const WebKit::WebRect& layerRect) const;
 
     scoped_ptr<WebKit::WebScrollbar> m_scrollbar;
     WebKit::WebScrollbarThemePainter m_painter;
     scoped_ptr<WebKit::WebScrollbarThemeGeometry> m_geometry;
     int m_scrollLayerId;
 
     GLenum m_textureFormat;
 
     scoped_refptr<CachingBitmapContentLayerUpdater> m_backTrackUpdater;
     scoped_refptr<CachingBitmapContentLayerUpdater> m_foreTrackUpdater;
     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