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

webrtc/media/base/mediaengine.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 152 matching lines @@
  protected:
   VOICE voice_;
   VIDEO video_;
 };
 
 enum DataChannelType { DCT_NONE = 0, DCT_RTP = 1, DCT_SCTP = 2, DCT_QUIC = 3 };
 
 class DataEngineInterface {
  public:
   virtual ~DataEngineInterface() {}
-  virtual DataMediaChannel* CreateChannel(DataChannelType type) = 0;
+  virtual DataMediaChannel* CreateChannel(DataChannelType type,
+                                          const MediaConfig& config) = 0;
   virtual const std::vector<DataCodec>& data_codecs() = 0;
 };
 
 webrtc::RtpParameters CreateRtpParametersWithOneEncoding();
 
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_BASE_MEDIAENGINE_H_