Adding IceConfig option to assume TURN/TURN candidate pairs will work.

webrtc/p2p/base/turnport.cc

 /*
  *  Copyright 2012 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 421 matching lines @@
     delete socket_;
   }
   socket_ = NULL;
 
   ResetNonce();
   PrepareAddress();
   ++allocate_mismatch_retries_;
 }
 
 Connection* TurnPort::CreateConnection(const Candidate& address,
-                                       CandidateOrigin origin) {
+                                       CandidateOrigin origin,
+                                       const IceConfig& config) {
   // TURN-UDP can only connect to UDP candidates.
   if (!SupportsProtocol(address.protocol())) {
     return NULL;
   }
 
   if (!IsCompatibleAddress(address.address())) {
     return NULL;
   }
 
   if (state_ == STATE_DISCONNECTED) {
     return NULL;
   }
 
   // Create an entry, if needed, so we can get our permissions set up correctly.
   CreateOrRefreshEntry(address.address());
 
   // A TURN port will have two candiates, STUN and TURN. STUN may not
   // present in all cases. If present stun candidate will be added first
   // and TURN candidate later.
   for (size_t index = 0; index < Candidates().size(); ++index) {
     if (Candidates()[index].type() == RELAY_PORT_TYPE) {
-      ProxyConnection* conn = new ProxyConnection(this, index, address);
+      ProxyConnection* conn = new ProxyConnection(this, index, address, config);
       AddOrReplaceConnection(conn);
       return conn;
     }
   }
   return NULL;
 }
 
 bool TurnPort::DestroyConnection(const rtc::SocketAddress& address) {
   Connection* conn = GetConnection(address);
   if (conn != nullptr) {
@@ skipping 1051 matching lines @@
   } else {
     state_ = STATE_UNBOUND;
     port_->DestroyConnection(ext_addr_);
   }
 }
 void TurnEntry::OnChannelBindTimeout() {
   state_ = STATE_UNBOUND;
   port_->DestroyConnection(ext_addr_);
 }
 }  // namespace cricket