Add in a new FrameConsumer interface, Decode API, and a RectangleUpdateDecoder abstraction.

remoting/base/decoder.h

Index: remoting/base/decoder.h
diff --git a/remoting/base/decoder.h b/remoting/base/decoder.h
index 75ffa03b25f4fc6ac141af1cf98a5635947a35bc..c8c77a779ee568106fbe45bb9a89cb20539eb0b3 100644
--- a/remoting/base/decoder.h
+++ b/remoting/base/decoder.h
@@ -90,6 +90,30 @@ class Decoder {
   // of BeginDecode() / EndDecode().
   virtual bool IsStarted() { return started_; }
 
+  // --- NEW API ---
+  // TODO(ajwong): This API is incorrect in the face of a streaming decode
+  // protocol like VP8.  However, it breaks the layering abstraction by
+  // depending on the network packet protocol buffer type. I'm going to go
+  // forward with it as is, and then refactor again to support streaming
+  // decodes.
+
+  // Initializes the decoder to draw into the given |frame|.  The |clip|
+  // specifies the region to draw into.  The clip region must fit inside
+  // the dimensions of frame. Failure to do so will CHECK Fail.
+  virtual void Initialize(scoped_refptr<media::VideoFrame> frame,
+                          const gfx::Rect& clip) {}
+
+  // Reset the decoder to an uninitialized state. Release all references to
+  // the initialized |frame|.  Initialize() must be called before the decoder
+  // is used again.
+  virtual void Reset() {}
+
+  // Feeds more data into the decoder.
+  virtual void DecodeBytes(const std::string& encoded_bytes) {}
+
+  // Returns true if decoder is ready to accept data via ProcessRectangleData.
+  virtual bool IsReadyForData() { return false; }
+
  protected:
   // Every decoder will have two internal states because there are three
   // kinds of messages send to PartialDecode().