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

cc/layer_impl.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 CC_LAYER_IMPL_H_
 #define CC_LAYER_IMPL_H_
 
 #include <string>
 
 #include "base/logging.h"
@@ skipping 280 matching lines @@
     ScrollbarAnimationController* scrollbarAnimationController() const { return m_scrollbarAnimationController.get(); }
 
     void setScrollbarOpacity(float opacity);
 
     void setHorizontalScrollbarLayer(ScrollbarLayerImpl*);
     ScrollbarLayerImpl* horizontalScrollbarLayer() { return m_horizontalScrollbarLayer; }
 
     void setVerticalScrollbarLayer(ScrollbarLayerImpl*);
     ScrollbarLayerImpl* verticalScrollbarLayer() { return m_verticalScrollbarLayer; }
 
+    void setHorizontalPinchZoomScrollbarLayer(ScrollbarLayerImpl*);
+    void setVerticalPinchZoomScrollbarLayer(ScrollbarLayerImpl*);
+
     gfx::Rect layerRectToContentRect(const gfx::RectF& layerRect) const;
 
     virtual skia::RefPtr<SkPicture> getPicture();
 
     virtual bool canClipSelf() const;
 
     virtual bool areVisibleResourcesReady() const;
 
     virtual scoped_ptr<LayerImpl> createLayerImpl(LayerTreeImpl*);
     virtual void pushPropertiesTo(LayerImpl*);
@@ skipping 107 matching lines @@
     scoped_refptr<LayerAnimationController> m_layerAnimationController;
 
     // Manages scrollbars for this layer
     scoped_ptr<ScrollbarAnimationController> m_scrollbarAnimationController;
 
     // Weak pointers to this layer's scrollbars, if it has them. Updated during
     // tree synchronization.
     ScrollbarLayerImpl* m_horizontalScrollbarLayer;
     ScrollbarLayerImpl* m_verticalScrollbarLayer;
 
+    // Weak pointers to this layer's pinch-zoom scrollbars, if it has them.
+    // Either both or neither will be present. Updated during tree
+    // synchronization.
+    ScrollbarLayerImpl* m_horizontalPinchZoomScrollbarLayer;
+    ScrollbarLayerImpl* m_verticalPinchZoomScrollbarLayer;
+
     // Group of properties that need to be computed based on the layer tree
     // hierarchy before layers can be drawn.
     DrawProperties<LayerImpl, RenderSurfaceImpl> m_drawProperties;
 
     DISALLOW_COPY_AND_ASSIGN(LayerImpl);
 };
 
 }
 
 #endif  // CC_LAYER_IMPL_H_