Restore the behavior where an ICE restart redetermines the ICE role.

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 428 matching lines @@
 
   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.
     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.
+  // 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.
+  if (transport->local_description() &&
+      IceCredentialsChanged(transport->local_description()->ice_ufrag,
+                            transport->local_description()->ice_pwd,
+                            tdesc.ice_ufrag, tdesc.ice_pwd)) {
+    IceRole new_ice_role =
+        (action == CA_OFFER) ? ICEROLE_CONTROLLING : ICEROLE_CONTROLLED;
+    SetIceRole(new_ice_role);
+  }
+
   return transport->SetLocalTransportDescription(tdesc, action, err);
 }
 
 bool TransportController::SetRemoteTransportDescription_n(
     const std::string& transport_name,
     const TransportDescription& tdesc,
     ContentAction action,
     std::string* err) {
   RTC_DCHECK(network_thread_->IsCurrent());
 
@@ skipping 205 matching lines @@
   }
   if (gathering_state_ != new_gathering_state) {
     gathering_state_ = new_gathering_state;
     signaling_thread_->Post(
         RTC_FROM_HERE, this, MSG_ICEGATHERINGSTATE,
         new rtc::TypedMessageData<IceGatheringState>(new_gathering_state));
   }
 }
 
 }  // namespace cricket