cc: Support mask layers in impl-side painting

cc/picture_layer.h

 // Copyright 2012 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_PICTURE_LAYER_H_
 #define CC_PICTURE_LAYER_H_
 
 #include "cc/contents_scaling_layer.h"
 #include "cc/layer.h"
 #include "cc/picture_pile.h"
@@ skipping 12 matching lines @@
   void clearClient() { client_ = 0; }
 
   // Implement Layer interface
   virtual bool drawsContent() const OVERRIDE;
   virtual scoped_ptr<LayerImpl> createLayerImpl(
       LayerTreeImpl* treeImpl) OVERRIDE;
   virtual void pushPropertiesTo(LayerImpl*) OVERRIDE;
   virtual void setNeedsDisplayRect(const gfx::RectF& layerRect) OVERRIDE;
   virtual void update(ResourceUpdateQueue&, const OcclusionTracker*,
                       RenderingStats&) OVERRIDE;
+  virtual void setIsMask(bool is_mask) OVERRIDE;
 
 protected:
   explicit PictureLayer(ContentLayerClient*);
   virtual ~PictureLayer();
 
 private:
   ContentLayerClient* client_;
   PicturePile pile_;
   // Invalidation to use the next time update is called.
   Region pending_invalidation_;
   // Invalidation from the last time update was called.
   Region pile_invalidation_;
+  bool is_mask_;
 };
 
 }  // namespace cc
 
 #endif  // CC_PICTURE_LAYER_H_