Fix potential teardown race conditions with TCPEngineTransport's PostTasks.

blimp/net/tcp_engine_transport.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BLIMP_NET_TCP_ENGINE_TRANSPORT_H_
 #define BLIMP_NET_TCP_ENGINE_TRANSPORT_H_
 
 #include <memory>
 
 #include "base/callback.h"
@@ skipping 31 matching lines @@
   std::unique_ptr<MessagePort> TakeMessagePort();
 
  private:
   void OnTCPConnectAccepted(int result);
 
   const net::IPEndPoint address_;
   net::NetLog* net_log_;
   std::unique_ptr<net::ServerSocket> server_socket_;
   std::unique_ptr<net::StreamSocket> accepted_socket_;
   net::CompletionCallback connect_callback_;
+  base::WeakPtrFactory<TCPEngineTransport> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TCPEngineTransport);
 };
 
 }  // namespace blimp
 
 #endif  // BLIMP_NET_TCP_ENGINE_TRANSPORT_H_