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

webrtc/media/base/mediaengine.h

Index: webrtc/media/base/mediaengine.h
diff --git a/webrtc/media/base/mediaengine.h b/webrtc/media/base/mediaengine.h
index 8083c8edaccd6ea1ef2a9c8a2b3dfce1618b1695..57a2c7e6e6e98841f37d1d289b9ec8a5ef77a8eb 100644
--- a/webrtc/media/base/mediaengine.h
+++ b/webrtc/media/base/mediaengine.h
@@ -170,7 +170,8 @@ 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;
 };