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

chrome/common/extensions/api/cast_streaming_udp_transport.idl

 // 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.
 
 // The <code>chrome.webrtc.castUdpTransport</code> API represents a UDP
 // transport for Cast RTP streams. This API is not useful when standalone
 // since it does not have send and receive methods.
 // It is used to configure the UDP transport used in Cast session.
 //
 // Valid transport IDs are positive and non-zero.
 namespace cast.streaming.udpTransport {
   // The UDP socket address and port.
   dictionary IPEndPoint {
     DOMString address;
     long port;
   };
 
   interface Functions {
     // Destroys a UDP transport.
     // |transportId| : The transport ID.
     [nocompile] static void destroy(long transportId);
 
     // Sets parameters for this UDP transport. This can only be called
     // once per transport.
     // |transportId| : The transport ID.
     // |destination| : The address and port to send packets to.
     [nocompile] static void setDestination(long transportId,
                                            IPEndPoint destination);
+
+    // Sets the options.
+    // Attributes of this object will be used to activate optional
+    // behaviours in the transport. Normally this is only used for
+    // experimentation. Must be called before setDestination.
+    [nocompile] static void setOptions(object options);
   };
 };