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

media/cast/test/sender.cc

Index: media/cast/test/sender.cc
diff --git a/media/cast/test/sender.cc b/media/cast/test/sender.cc
index a90422291cd258e6a55e363494a4ad4189d67a70..afe71455ccd04a3899950e76df77cc139e8484e0 100644
--- a/media/cast/test/sender.cc
+++ b/media/cast/test/sender.cc
@@ -322,6 +322,7 @@ int main(int argc, char** argv) {
           NULL,  // net log.
           cast_environment->Clock(),
           remote_endpoint,
+          "",  // options
           base::Bind(&UpdateCastTransportStatus),
           base::Bind(&LogRawEvents, cast_environment),
           base::TimeDelta::FromSeconds(1),