Add SocketFactoryInterface::Prepare and fix how symmetric NAT is determined

webrtc/p2p/stunprober/stunprober_dependencies.h

 /*
  *  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 17 matching lines @@
  public:
   explicit Socket(rtc::AsyncSocket* socket) : socket_(socket) {
     socket_->SignalReadEvent.connect(this, &Socket::OnReadEvent);
     socket_->SignalWriteEvent.connect(this, &Socket::OnWriteEvent);
   }
 
   int Connect(const rtc::SocketAddress& addr) override {
     return MapResult(socket_->Connect(addr));
   }
 
-  int Bind(const rtc::SocketAddress& addr) override {
-    return MapResult(socket_->Bind(addr));
-  }
-
   int SendTo(const rtc::SocketAddress& addr,
              char* buf,
              size_t buf_len,
              AsyncCallback callback) override {
     write_ = NetworkWrite(addr, buf, buf_len, callback);
     return MapResult(socket_->SendTo(buf, buf_len, addr));
   }
 
   int RecvFrom(char* buf,
                size_t buf_len,
@@ skipping 121 matching lines @@
 
   void OnMessage(rtc::Message* msg) {
     rtc::scoped_ptr<CallbackMessageData> callback(
         reinterpret_cast<CallbackMessageData*>(msg->pdata));
     callback->callback_();
   }
 };
 
 }  // namespace stunprober
 #endif  // WEBRTC_P2P_STUNPROBER_STUNPROBER_DEPENDENCIES_H_