Allow p2p UDP packages to set DSCP

net/udp/udp_socket_libevent.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.
 
 #ifndef NET_UDP_UDP_SOCKET_LIBEVENT_H_
 #define NET_UDP_UDP_SOCKET_LIBEVENT_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 133 matching lines @@
   // Note: the behavior of |SetMulticastLoopbackMode| is slightly
   // different between Windows and Unix-like systems. The inconsistency only
   // happens when there are more than one applications on the same host
   // joined to the same multicast group while having different settings on
   // multicast loopback mode. On Windows, the applications with loopback off
   // will not RECEIVE the loopback packets; while on Unix-like systems, the
   // applications with loopback off will not SEND the loopback packets to
   // other applications on the same host. See MSDN: http://goo.gl/6vqbj
   int SetMulticastLoopbackMode(bool loopback);
 
+  // Set the differentiated services flags on outgoing packets. May not
+  // do anything on some platforms.
+  int SetDiffServCodePoint(DiffServCodePoint dscp);
+
  private:
   static const int kInvalidSocket = -1;
 
   enum SocketOptions {
     SOCKET_OPTION_REUSE_ADDRESS  = 1 << 0,
     SOCKET_OPTION_BROADCAST      = 1 << 1,
     SOCKET_OPTION_MULTICAST_LOOP = 1 << 2
   };
 
   class ReadWatcher : public base::MessageLoopForIO::Watcher {
@@ skipping 110 matching lines @@
   CompletionCallback write_callback_;
 
   BoundNetLog net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(UDPSocketLibevent);
 };
 
 }  // namespace net
 
 #endif  // NET_UDP_UDP_SOCKET_LIBEVENT_H_