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

media/cast/test/cast_benchmarks.cc

Index: media/cast/test/cast_benchmarks.cc
diff --git a/media/cast/test/cast_benchmarks.cc b/media/cast/test/cast_benchmarks.cc
index deec12ca538a56be1a05b3e0bd9b9c8fa0ac0f01..6a6f8b24e82ddacdc2578e8c6b0a69f3fde6950e 100644
--- a/media/cast/test/cast_benchmarks.cc
+++ b/media/cast/test/cast_benchmarks.cc
@@ -302,6 +302,7 @@ class RunOneBenchmark {
             NULL,
             testing_clock_sender_,
             dummy_endpoint,
+            make_scoped_ptr(new base::DictionaryValue),
             base::Bind(&UpdateCastTransportStatus),
             base::Bind(&IgnoreRawEvents),
             base::TimeDelta::FromSeconds(1),