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

net/udp/datagram_socket.h

 // Copyright (c) 2011 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 NET_UDP_DATAGRAM_SOCKET_H_
 #define NET_UDP_DATAGRAM_SOCKET_H_
 
 #include "net/base/net_export.h"
 
 namespace net {
@@ skipping 20 matching lines @@
   virtual int GetPeerAddress(IPEndPoint* address) const = 0;
 
   // Copy the local udp address into |address| and return a network error code.
   // (similar to getsockname)
   virtual int GetLocalAddress(IPEndPoint* address) const = 0;
 
   // Switch to use non-blocking IO. Must be called right after construction and
   // before other calls.
   virtual void UseNonBlockingIO() = 0;
 
+  // Requests that packets sent by this socket not be fragment, either locally
+  // by the host, or by routers (via the DF bit in the IPv4 packet header).
+  // May not be supported by all platforms. Returns a return a network error
+  // code if there was a problem, but the socket will still be usable. Can not
+  // return ERR_IO_PENDING.
+  virtual int SetDoNotFragment() = 0;
+
   // Gets the NetLog for this socket.
   virtual const BoundNetLog& NetLog() const = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_UDP_DATAGRAM_SOCKET_H_