cc: Add strict layer property change checking and handle bounds changes during paint.

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index 40909cf0cdb614629fa66cd08a064c36ff1246d1..51380152d34ed0a498b7a652984e320e6a0d0aac 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -268,6 +268,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
 
   // These methods typically need to be overwritten by derived classes.
   virtual bool DrawsContent() const;
+  virtual void PrepareToUpdate();
   virtual void Update(ResourceUpdateQueue* queue,
                       const OcclusionTracker* occlusion,
                       RenderingStats* stats) {}
@@ -379,6 +380,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
 
   void SetNeedsCommit();
   void SetNeedsFullTreeSync();
+  bool IsPropertyChangeAllowed() const;
 
   // This flag is set when layer need repainting/updating.
   bool needs_display_;
@@ -473,6 +475,9 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
 
   gfx::Transform impl_transform_;
 
+  // These properties that can change during Update().
+  gfx::Size last_bounds_;
+
   WebKit::WebLayerScrollClient* layer_scroll_client_;
 
   DrawProperties<Layer, RenderSurface> draw_properties_;