cc: add layer usage hint to texture layer

cc/texture_layer.h

Index: cc/texture_layer.h
diff --git a/cc/texture_layer.h b/cc/texture_layer.h
index f85edb6138e199e4be9c596caa0e6c3c7891063e..5ccca15215141975a12876e4792c12adc01aef2a 100644
--- a/cc/texture_layer.h
+++ b/cc/texture_layer.h
@@ -24,7 +24,7 @@ class CC_EXPORT TextureLayer : public Layer {
   // If this texture layer requires special preparation logic for each frame
   // driven by the compositor, pass in a non-nil client. Pass in a nil client
   // pointer if texture updates are driven by an external process.
-  static scoped_refptr<TextureLayer> Create(TextureLayerClient* client);
+  static scoped_refptr<TextureLayer> Create(TextureLayerClient* client, bool single_buffer = false);
 
   // Used when mailbox names are specified instead of texture IDs.
   static scoped_refptr<TextureLayer> CreateForMailbox();
@@ -78,7 +78,7 @@ class CC_EXPORT TextureLayer : public Layer {
   virtual bool CanClipSelf() const OVERRIDE;
 
  protected:
-  TextureLayer(TextureLayerClient* client, bool uses_mailbox);
+  TextureLayer(TextureLayerClient* client, bool uses_mailbox, bool single_buffer);
   virtual ~TextureLayer();
 
  private:
@@ -99,6 +99,9 @@ class CC_EXPORT TextureLayer : public Layer {
   TextureMailbox texture_mailbox_;
   bool own_mailbox_;
 
+  // indicate the layer usage, it's a const after set in constructor
+  bool single_buffer_;
+
   DISALLOW_COPY_AND_ASSIGN(TextureLayer);
 };