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

chrome/renderer/media/cast_session_delegate.cc

Index: chrome/renderer/media/cast_session_delegate.cc
diff --git a/chrome/renderer/media/cast_session_delegate.cc b/chrome/renderer/media/cast_session_delegate.cc
index 3d16c5b8d40e16fd66b3ca26f97bdc94db8fa958..66ea705f3b13bb7106e8ece0ecea1d35d874ca40 100644
--- a/chrome/renderer/media/cast_session_delegate.cc
+++ b/chrome/renderer/media/cast_session_delegate.cc
@@ -82,7 +82,8 @@ void CastSessionDelegate::StartVideo(
       create_video_encode_mem_cb);
 }
 
-void CastSessionDelegate::StartUDP(const net::IPEndPoint& remote_endpoint) {
+void CastSessionDelegate::StartUDP(const net::IPEndPoint& remote_endpoint,
+                                   const std::string& options) {
   DCHECK(io_message_loop_proxy_->BelongsToCurrentThread());
 
   // CastSender uses the renderer's IO thread as the main thread. This reduces
@@ -100,6 +101,7 @@ void CastSessionDelegate::StartUDP(const net::IPEndPoint& remote_endpoint) {
   // destruction of CastTransportSenderIPC, and they both share the same thread.
   cast_transport_.reset(new CastTransportSenderIPC(
       remote_endpoint,
+      options,
       base::Bind(&CastSessionDelegate::StatusNotificationCB,
                  base::Unretained(this)),
       base::Bind(&CastSessionDelegate::LogRawEvents, base::Unretained(this))));