Fix for data channels perpetually stuck in "closing" state.

webrtc/api/datachannel.h

 /*
  *  Copyright 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 140 matching lines @@
 
   // The following methods are for SCTP only.
 
   // Sets the SCTP sid and adds to transport layer if not set yet. Should only
   // be called once.
   void SetSctpSid(int sid);
   // Called when the transport channel is created.
   // Only needs to be called for SCTP data channels.
   void OnTransportChannelCreated();
   // Called when the transport channel is destroyed.
+  // This method makes sure the DataChannel is disconnected and changes state
+  // to kClosed.
   void OnTransportChannelDestroyed();
 
   // The following methods are for RTP only.
 
   // Set the SSRC this channel should use to send data on the
   // underlying data engine. |send_ssrc| == 0 means that the channel is no
   // longer part of the session negotiation.
   void SetSendSsrc(uint32_t send_ssrc);
   // Set the SSRC this channel should use to receive data from the
   // underlying data engine.
@@ skipping 102 matching lines @@
   PROXY_CONSTMETHOD0(int, id)
   PROXY_CONSTMETHOD0(DataState, state)
   PROXY_CONSTMETHOD0(uint64_t, buffered_amount)
   PROXY_METHOD0(void, Close)
   PROXY_METHOD1(bool, Send, const DataBuffer&)
 END_SIGNALING_PROXY()
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_DATACHANNEL_H_