Only do full tree sync if tree is actually changed, otherwise just push properties

cc/layer_tree_host.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_TREE_HOST_H_
 #define CC_LAYER_TREE_HOST_H_
 
 #include <limits>
 
 #include "base/basictypes.h"
@@ skipping 166 matching lines @@
     void renderingStats(RenderingStats*) const;
 
     const RendererCapabilities& rendererCapabilities() const;
 
     // Test only hook
     void loseContext(int numTimes);
 
     void setNeedsAnimate();
     // virtual for testing
     virtual void setNeedsCommit();
+    virtual void setNeedsFullTreeSync();
     void setNeedsRedraw();
     bool commitRequested() const;
 
     void setAnimationEvents(scoped_ptr<AnimationEventsVector>, base::Time wallClockTime);
     virtual void didAddAnimation();
 
     Layer* rootLayer() { return m_rootLayer.get(); }
     const Layer* rootLayer() const { return m_rootLayer.get(); }
     void setRootLayer(scoped_refptr<Layer>);
 
@@ skipping 64 matching lines @@
     void setPrioritiesForSurfaces(size_t surfaceMemoryBytes);
     void setPrioritiesForLayers(const LayerList&);
     size_t calculateMemoryForRenderSurfaces(const LayerList& updateList);
 
     void animateLayers(base::TimeTicks monotonicTime);
     bool animateLayersRecursive(Layer* current, base::TimeTicks time);
     void setAnimationEventsRecursive(const AnimationEventsVector&, Layer*, base::Time wallClockTime);
 
     bool m_animating;
     bool m_needsAnimateLayers;
+    bool m_needsFullTreeSync;
 
     base::CancelableClosure m_prepaintCallback;
 
     LayerTreeHostClient* m_client;
     scoped_ptr<Proxy> m_proxy;
 
     int m_commitNumber;
     RenderingStats m_renderingStats;
 
     bool m_rendererInitialized;
@@ skipping 31 matching lines @@
     size_t m_partialTextureUpdateRequests;
 
     static bool s_needsFilterContext;
 
     DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYER_TREE_HOST_H_