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

webrtc/p2p/base/relayport.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.
  */
 #include <algorithm>
@@ skipping 258 matching lines @@
 
 void RelayPort::PrepareAddress() {
   // We initiate a connect on the first entry.  If this completes, it will fill
   // in the server address as the address of this port.
   ASSERT(entries_.size() == 1);
   entries_[0]->Connect();
   ready_ = false;
 }
 
 Connection* RelayPort::CreateConnection(const Candidate& address,
-                                        CandidateOrigin origin) {
+                                        CandidateOrigin origin,
+                                        const IceConfig& config) {
   // We only create conns to non-udp sockets if they are incoming on this port
   if ((address.protocol() != UDP_PROTOCOL_NAME) &&
       (origin != ORIGIN_THIS_PORT)) {
     return 0;
   }
 
   // We don't support loopback on relays
   if (address.type() == Type()) {
     return 0;
   }
 
   if (!IsCompatibleAddress(address.address())) {
     return 0;
   }
 
   size_t index = 0;
   for (size_t i = 0; i < Candidates().size(); ++i) {
     const Candidate& local = Candidates()[i];
     if (local.protocol() == address.protocol()) {
       index = i;
       break;
     }
   }
 
-  Connection * conn = new ProxyConnection(this, index, address);
+  Connection* conn = new ProxyConnection(this, index, address, config);
   AddOrReplaceConnection(conn);
   return conn;
 }
 
 int RelayPort::SendTo(const void* data, size_t size,
                       const rtc::SocketAddress& addr,
                       const rtc::PacketOptions& options,
                       bool payload) {
   // Try to find an entry for this specific address.  Note that the first entry
   // created was not given an address initially, so it can be set to the first
@@ skipping 522 matching lines @@
   if (rtc::TimeMillis() - start_time_ <= kRetryTimeout)
     entry_->ScheduleKeepAlive();
 }
 
 void AllocateRequest::OnTimeout() {
   LOG(INFO) << "Allocate request timed out";
   entry_->HandleConnectFailure(connection_->socket());
 }
 
 }  // namespace cricket