Cast: Let the extension control if DSCP is on or off.

chrome/renderer/media/cast_udp_transport.cc

 // Copyright 2013 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.
 
 #include "chrome/renderer/media/cast_udp_transport.h"
 
 #include "chrome/renderer/media/cast_session.h"
 
 CastUdpTransport::CastUdpTransport(
     const scoped_refptr<CastSession>& session)
     : cast_session_(session), weak_factory_(this) {
 }
 
 CastUdpTransport::~CastUdpTransport() {
 }
 
 void CastUdpTransport::SetDestination(const net::IPEndPoint& remote_address) {
   VLOG(1) << "CastUdpTransport::SetDestination = "
           << remote_address.ToString();
   remote_address_ = remote_address;
-  cast_session_->StartUDP(remote_address);
+  cast_session_->StartUDP(remote_address, options_);
 }
+
+void CastUdpTransport::SetOptions(const std::string& options) {
+  options_ = options;
+}