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

cc/layer.h

 // Copyright 2010 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_H_
 #define CC_LAYER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 255 matching lines @@
     LayerAnimationController* layerAnimationController() { return m_layerAnimationController.get(); }
     void setLayerAnimationController(scoped_refptr<LayerAnimationController>);
     scoped_refptr<LayerAnimationController> releaseLayerAnimationController();
 
     void setLayerAnimationDelegate(WebKit::WebAnimationDelegate* layerAnimationDelegate) { m_layerAnimationDelegate = layerAnimationDelegate; }
 
     bool hasActiveAnimation() const;
 
     virtual void notifyAnimationStarted(const AnimationEvent&, double wallClockTime);
     virtual void notifyAnimationFinished(double wallClockTime);
+    virtual void notifyAnimationPropertyUpdate(const AnimationEvent& event);
 
     void addLayerAnimationEventObserver(LayerAnimationEventObserver* animationObserver);
     void removeLayerAnimationEventObserver(LayerAnimationEventObserver* animationObserver);
 
     virtual Region visibleContentOpaqueRegion() const;
 
     virtual ScrollbarLayer* toScrollbarLayer();
 
     gfx::Rect layerRectToContentRect(const gfx::RectF& layerRect) const;
 
@@ skipping 119 matching lines @@
     WebKit::WebLayerScrollClient* m_layerScrollClient;
 
     DrawProperties<Layer, RenderSurface> m_drawProperties;
 };
 
 void sortLayers(std::vector<scoped_refptr<Layer> >::iterator, std::vector<scoped_refptr<Layer> >::iterator, void*);
 
 }  // namespace cc
 
 #endif  // CC_LAYER_H_