Only generate one CNAME per PeerConnection.

webrtc/pc/mediasession.cc

 /*
  *  Copyright 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 205 matching lines @@
   for (StreamParamsVec::const_iterator it = params_vec.begin();
        it != params_vec.end(); ++it) {
     if (cname == it->cname)
       return &*it;
   }
   return NULL;
 }
 
 // Generates a new CNAME or the CNAME of an already existing StreamParams
 // if a StreamParams exist for another Stream in streams with sync_label
 // sync_label.

[pthatcher1, 2016/04/12 22:43:14]

This comment is no longer accurate.

 static bool GenerateCname(const StreamParamsVec& params_vec,
                           const MediaSessionOptions::Streams& streams,
                           const std::string& synch_label,

[pthatcher1, 2016/04/12 22:43:14]

This parameter is no longer used.

                           std::string* cname) {
   ASSERT(cname != NULL);
   if (!cname)
     return false;
 
-  // Check if a CNAME exist for any of the other synched streams.
+  // Check if a CNAME exist for any of the other streams.

[pthatcher1, 2016/04/12 22:43:14]

exist => exists

   for (MediaSessionOptions::Streams::const_iterator stream_it = streams.begin();
        stream_it != streams.end() ; ++stream_it) {

[pthatcher1, 2016/04/12 22:43:14]

While you're in here, can you update this to a c++11-style for loop?

for (MediaSessionOptions::Stream stream : streams)

-    if (synch_label != stream_it->sync_label)
-      continue;
 
     // groupid is empty for StreamParams generated using
     // MediaSessionDescriptionFactory.
     const StreamParams* param = GetStreamByIds(params_vec, "", stream_it->id);
     if (param) {
       *cname = param->cname;
       return true;
     }
   }
   // No other stream seems to exist that we should sync with.
@@ skipping 1744 matching lines @@
       GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_VIDEO));
 }
 
 const DataContentDescription* GetFirstDataContentDescription(
     const SessionDescription* sdesc) {
   return static_cast<const DataContentDescription*>(
       GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_DATA));
 }
 
 }  // namespace cricket