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

cc/layer.cc

 // 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.
 
 #include "cc/layer.h"
 
 #include "cc/animation.h"
 #include "cc/animation_events.h"
 #include "cc/layer_animation_controller.h"
 #include "cc/layer_impl.h"
@@ skipping 863 matching lines @@
     if (m_layerAnimationDelegate)
         m_layerAnimationDelegate->notifyAnimationStarted(wallClockTime);
 }
 
 void Layer::notifyAnimationFinished(double wallClockTime)
 {
     if (m_layerAnimationDelegate)
         m_layerAnimationDelegate->notifyAnimationFinished(wallClockTime);
 }
 
+void Layer::notifyAnimationPropertyUpdate(const AnimationEvent& event)
+{
+    if (event.targetProperty == Animation::Opacity)
+        setOpacity(event.value);
+}
+
 void Layer::addLayerAnimationEventObserver(LayerAnimationEventObserver* animationObserver)
 {
     if (!m_layerAnimationObservers.HasObserver(animationObserver))
         m_layerAnimationObservers.AddObserver(animationObserver);
 }
 
 void Layer::removeLayerAnimationEventObserver(LayerAnimationEventObserver* animationObserver)
 {
     m_layerAnimationObservers.RemoveObserver(animationObserver);
 }
 
 Region Layer::visibleContentOpaqueRegion() const
 {
     if (contentsOpaque())
         return visibleContentRect();
     return Region();
 }
 
 ScrollbarLayer* Layer::toScrollbarLayer()
 {
     return 0;
 }
 
 void sortLayers(std::vector<scoped_refptr<Layer> >::iterator, std::vector<scoped_refptr<Layer> >::iterator, void*)
 {
     // Currently we don't use z-order to decide what to paint, so there's no need to actually sort Layers.
 }
 
 }  // namespace cc