We don't want to tick animation controllers for non-active layers

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 321 matching lines @@
 
     // Returns the index of the child or -1 if not found.
     int indexOfChild(const Layer*);
 
     // This should only be called from removeFromParent.
     void removeChild(Layer*);
 
     // LayerAnimationValueObserver implementation.
     virtual void OnOpacityAnimated(float) OVERRIDE;
     virtual void OnTransformAnimated(const gfx::Transform&) OVERRIDE;
+    virtual bool IsActive() const OVERRIDE;
 
     LayerList m_children;
     Layer* m_parent;
 
     // Layer instances have a weak pointer to their LayerTreeHost.
     // This pointer value is nil when a Layer is not in a tree and is
     // updated via setLayerTreeHost() if a layer moves between trees.
     LayerTreeHost* m_layerTreeHost;
 
     ObserverList<LayerAnimationEventObserver> m_layerAnimationObservers;
@@ skipping 49 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_