Adding logs to track potential cause of not starting port allocation.

webrtc/p2p/base/transportcontroller.cc

 /*
  *  Copyright 2015 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 437 matching lines @@
     ContentAction action,
     std::string* err) {
   RTC_DCHECK(network_thread_->IsCurrent());
 
   Transport* transport = GetTransport_n(transport_name);
   if (!transport) {
     // If we didn't find a transport, that's not an error;
     // it could have been deleted as a result of bundling.
     // TODO(deadbeef): Make callers smarter so they won't attempt to set a
     // description on a deleted transport.
+    // This assumes we always bundle all media on the audio transport, so I
+    // only log a message here.
+    if (transport_name == CN_AUDIO) {

[pthatcher1, 2016/09/08 17:55:27]

We don't always bundle on audio, and this would log an error for every single
PeerConnection that uses only data channels. 

You might be better off logging all transports that are in the
TransportController after every call to PeerConnecction::SetLocalDescription.

[honghaiz3, 2016/09/08 21:30:11]

If we are using data-channel only, then the transport should not have been
deleted due to bundle (so transport should not be nullptr), right?

+      LOG(LS_ERROR) << "No transport is found for audio when setting "
+                    << "local transport description";
+    }
     return true;
   }
 
   // Older versions of Chrome expect the ICE role to be re-determined when an
   // ICE restart occurs, and also don't perform conflict resolution correctly,
   // so for now we can't safely stop doing this, unless the application opts in
   // by setting |redetermine_role_on_ice_restart_| to false.
   // See: https://bugs.chromium.org/p/chromium/issues/detail?id=628676
   // TODO(deadbeef): Remove this when these old versions of Chrome reach a low
   // enough population.
@@ skipping 228 matching lines @@
         RTC_FROM_HERE, this, MSG_ICEGATHERINGSTATE,
         new rtc::TypedMessageData<IceGatheringState>(new_gathering_state));
   }
 }
 
 void TransportController::OnDtlsHandshakeError(rtc::SSLHandshakeError error) {
   SignalDtlsHandshakeError(error);
 }
 
 }  // namespace cricket