Remove calls to deprecated MessageLoop methods in content.

content/renderer/media/media_stream_video_track_unittest.cc

Index: content/renderer/media/media_stream_video_track_unittest.cc
diff --git a/content/renderer/media/media_stream_video_track_unittest.cc b/content/renderer/media/media_stream_video_track_unittest.cc
index 8e23c902b111ad58279ce16c4425a2df20a34972..85b7bdafab931b275f71c8025785bb5bc5fd8fb1 100644
--- a/content/renderer/media/media_stream_video_track_unittest.cc
+++ b/content/renderer/media/media_stream_video_track_unittest.cc
@@ -124,7 +124,7 @@ TEST_F(MediaStreamVideoTrackTest, AddAndRemoveSink) {
                     MediaStreamVideoSource::kDefaultHeight));
   mock_source()->DeliverVideoFrame(frame);
   // Wait for the IO thread to complete delivering frames.
-  io_message_loop()->RunUntilIdle();
+  base::RunLoop().RunUntilIdle();
   EXPECT_EQ(2, sink.number_of_frames());
 }