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

webrtc/media/base/rtpdataengine.cc

Index: webrtc/media/base/rtpdataengine.cc
diff --git a/webrtc/media/base/rtpdataengine.cc b/webrtc/media/base/rtpdataengine.cc
index a0c2cfc96eb19721807365f5c2ed5c758e20b24d..12a37fa180f59ed36f3ec2901aca3d2e1212a488 100644
--- a/webrtc/media/base/rtpdataengine.cc
+++ b/webrtc/media/base/rtpdataengine.cc
@@ -40,11 +40,12 @@ RtpDataEngine::RtpDataEngine() {
 }
 
 DataMediaChannel* RtpDataEngine::CreateChannel(
-    DataChannelType data_channel_type) {
+    DataChannelType data_channel_type,
+    const MediaConfig& config) {
   if (data_channel_type != DCT_RTP) {
     return NULL;
   }
-  return new RtpDataMediaChannel();
+  return new RtpDataMediaChannel(config);
 }
 
 static const DataCodec* FindCodecByName(const std::vector<DataCodec>& codecs,
@@ -56,7 +57,8 @@ static const DataCodec* FindCodecByName(const std::vector<DataCodec>& codecs,
   return nullptr;
 }
 
-RtpDataMediaChannel::RtpDataMediaChannel() {
+RtpDataMediaChannel::RtpDataMediaChannel(const MediaConfig& config)
+    : DataMediaChannel(config) {
   Construct();
 }
 
@@ -341,4 +343,8 @@ bool RtpDataMediaChannel::SendData(
   return true;
 }
 
+rtc::DiffServCodePoint RtpDataMediaChannel::PreferredDscp() const {
+  return rtc::DSCP_AF41;
+}
+
 }  // namespace cricket