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

webrtc/p2p/base/tcpport.h

 /*
  *  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 32 matching lines @@
                                 max_port, username, password, allow_listen);
     if (!port->Init()) {
       delete port;
       port = NULL;
     }
     return port;
   }
   ~TCPPort() override;
 
   Connection* CreateConnection(const Candidate& address,
-                               CandidateOrigin origin) override;
+                               CandidateOrigin origin,
+                               const IceConfig& config) override;
 
   void PrepareAddress() override;
 
   int GetOption(rtc::Socket::Option opt, int* value) override;
   int SetOption(rtc::Socket::Option opt, int value) override;
   int GetError() override;
   bool SupportsProtocol(const std::string& protocol) const override {
     return protocol == TCP_PROTOCOL_NAME || protocol == SSLTCP_PROTOCOL_NAME;
   }
 
@@ skipping 49 matching lines @@
   rtc::AsyncPacketSocket* socket_;
   int error_;
   std::list<Incoming> incoming_;
 
   friend class TCPConnection;
 };
 
 class TCPConnection : public Connection {
  public:
   // Connection is outgoing unless socket is specified
-  TCPConnection(TCPPort* port, const Candidate& candidate,
+  TCPConnection(TCPPort* port,
+                const Candidate& candidate,
+                const IceConfig& config,
                 rtc::AsyncPacketSocket* socket = 0);
   ~TCPConnection() override;
 
   int Send(const void* data,
            size_t size,
            const rtc::PacketOptions& options) override;
   int GetError() override;
 
   rtc::AsyncPacketSocket* socket() { return socket_.get(); }
 
@@ skipping 49 matching lines @@
 
   // Allow test case to overwrite the default timeout period.
   int reconnection_timeout_;
 
   friend class TCPPort;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_TCPPORT_H_