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

cc/layers/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_LAYERS_LAYER_H_
 #define CC_LAYERS_LAYER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 250 matching lines @@
   const Layer* replica_layer() const { return replica_layer_.get(); }
 
   bool has_mask() const { return !!mask_layer_; }
   bool has_replica() const { return !!replica_layer_; }
   bool replica_has_mask() const {
     return replica_layer_ && (mask_layer_ || replica_layer_->mask_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) {}
   virtual bool NeedMoreUpdates();
   virtual void SetIsMask(bool is_mask) {}
 
   void SetDebugName(const std::string& debug_name);
 
   virtual void PushPropertiesTo(LayerImpl* layer);
 
@@ skipping 91 matching lines @@
 
  protected:
   friend class LayerImpl;
   friend class TreeSynchronizer;
   virtual ~Layer();
 
   Layer();
 
   void SetNeedsCommit();
   void SetNeedsFullTreeSync();
+  bool IsPropertyChangeAllowed() const;
 
   // This flag is set when layer need repainting/updating.
   bool needs_display_;
 
   // Tracks whether this layer may have changed stacking order with its
   // siblings.
   bool stacking_order_changed_;
 
   // The update rect is the region of the compositor resource that was
   // actually updated by the compositor. For layers that may do updating
@@ skipping 74 matching lines @@
   // Replica layer used for reflections.
   scoped_refptr<Layer> replica_layer_;
 
   // Transient properties.
   float raster_scale_;
   bool automatically_compute_raster_scale_;
   bool bounds_contain_page_scale_;
 
   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_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_H_