Set the preferred DSCP value for Rtp data channel to be DSCP_AF41.

webrtc/media/base/mediachannel.h

 /*
  *  Copyright (c) 2004 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 1138 matching lines @@
   enum Error {
     ERROR_NONE = 0,                       // No error.
     ERROR_OTHER,                          // Other errors.
     ERROR_SEND_SRTP_ERROR = 200,          // Generic SRTP failure.
     ERROR_SEND_SRTP_AUTH_FAILED,          // Failed to authenticate packets.
     ERROR_RECV_SRTP_ERROR,                // Generic SRTP failure.
     ERROR_RECV_SRTP_AUTH_FAILED,          // Failed to authenticate packets.
     ERROR_RECV_SRTP_REPLAY,               // Packet replay detected.
   };
 
+  DataMediaChannel() {}
+  DataMediaChannel(const MediaConfig& config) : MediaChannel(config) {}
   virtual ~DataMediaChannel() {}
 
   virtual bool SetSendParameters(const DataSendParameters& params) = 0;
   virtual bool SetRecvParameters(const DataRecvParameters& params) = 0;
 
   // TODO(pthatcher): Implement this.
   virtual bool GetStats(DataMediaInfo* info) { return true; }
 
   virtual bool SetSend(bool send) = 0;
   virtual bool SetReceive(bool receive) = 0;
@@ skipping 12 matching lines @@
   // Signal when the media channel is ready to send the stream. Arguments are:
   //     writable(bool)
   sigslot::signal1<bool> SignalReadyToSend;
   // Signal for notifying that the remote side has closed the DataChannel.
   sigslot::signal1<uint32_t> SignalStreamClosedRemotely;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_BASE_MEDIACHANNEL_H_