Add a SetDoNotFragment() method to DatagramSocket, and call this for

jingle/glue/proxy_resolving_client_socket.h

 // Copyright (c) 2012 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.
 //
 // This StreamSocket implementation wraps a ClientSocketHandle that is created
 // from the client socket pool after resolving proxies.
 
 #ifndef JINGLE_GLUE_PROXY_RESOLVING_CLIENT_SOCKET_H_
 #define JINGLE_GLUE_PROXY_RESOLVING_CLIENT_SOCKET_H_
 
@@ skipping 43 matching lines @@
 
   // net::StreamSocket implementation.
   int Read(net::IOBuffer* buf,
            int buf_len,
            const net::CompletionCallback& callback) override;
   int Write(net::IOBuffer* buf,
             int buf_len,
             const net::CompletionCallback& callback) override;
   int SetReceiveBufferSize(int32_t size) override;
   int SetSendBufferSize(int32_t size) override;
+  int SetDoNotFragment(bool do_not_fragment) override;
   int Connect(const net::CompletionCallback& callback) override;
   void Disconnect() override;
   bool IsConnected() const override;
   bool IsConnectedAndIdle() const override;
   int GetPeerAddress(net::IPEndPoint* address) const override;
   int GetLocalAddress(net::IPEndPoint* address) const override;
   const net::BoundNetLog& NetLog() const override;
   void SetSubresourceSpeculation() override;
   void SetOmniboxSpeculation() override;
   bool WasEverUsed() const override;
@@ skipping 37 matching lines @@
   net::CompletionCallback user_connect_callback_;
 
   base::WeakPtrFactory<ProxyResolvingClientSocket> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyResolvingClientSocket);
 };
 
 }  // namespace jingle_glue
 
 #endif  // JINGLE_GLUE_PROXY_RESOLVING_CLIENT_SOCKET_H_