Remove video_channel() from Session interface

remoting/protocol/video_reader.h

Index: remoting/protocol/video_reader.h
diff --git a/remoting/protocol/video_reader.h b/remoting/protocol/video_reader.h
index ba39be3c1f702942c8a1c052c91ad7acd30d5b09..726144fc783136edcf18c14ce212c48fc3f7a2ee 100644
--- a/remoting/protocol/video_reader.h
+++ b/remoting/protocol/video_reader.h
@@ -25,12 +25,17 @@ class VideoReader {
  public:
   static VideoReader* Create(const SessionConfig* config);
 
+  // The callback is called when initialization is finished. The
+  // parameter is set to true on success.
+  typedef base::Callback<void(bool)> InitializedCallback;
+
   virtual ~VideoReader();
 
   // Initializies the reader. Doesn't take ownership of either |connection|
   // or |video_stub|.
   virtual void Init(Session* session,
-                    VideoStub* video_stub) = 0;
+                    VideoStub* video_stub,
+                    const InitializedCallback& callback) = 0;
 
  protected:
   VideoReader() { }