Implement ObjC DataChannel wrapper

R=fischman@webrtc.org
BUG=3112

Review URL: https://webrtc-codereview.appspot.com/16369004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6031 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/talk/app/webrtc/datachannelinterface.h b/talk/app/webrtc/datachannelinterface.h
index 7be8a50..57fe200 100644
--- a/talk/app/webrtc/datachannelinterface.h
+++ b/talk/app/webrtc/datachannelinterface.h
@@ -97,7 +97,9 @@
 
 class DataChannelInterface : public talk_base::RefCountInterface {
  public:
-  enum DataState {  // Keep in sync with DataChannel.java:State.
+  // Keep in sync with DataChannel.java:State and
+  // RTCDataChannel.h:RTCDataChannelState.
+  enum DataState {
     kConnecting,
     kOpen,  // The DataChannel is ready to send data.
     kClosing,