Replace MessageLoopProxy with SingleThreadTaskRunner for the rest of media/.

media/audio/audio_output_controller_unittest.cc

Index: media/audio/audio_output_controller_unittest.cc
diff --git a/media/audio/audio_output_controller_unittest.cc b/media/audio/audio_output_controller_unittest.cc
index 0347d0d4b40563d9f78fe5a451d40db352231d5c..e77d3d51f0da1641a997cb7a2ce4f59e657fa82c 100644
--- a/media/audio/audio_output_controller_unittest.cc
+++ b/media/audio/audio_output_controller_unittest.cc
@@ -166,7 +166,7 @@ class AudioOutputControllerTest : public testing::Test {
 
     // Simulate a device change event to AudioOutputController from the
     // AudioManager.
-    audio_manager_->GetMessageLoop()->PostTask(
+    audio_manager_->GetTaskRunner()->PostTask(
         FROM_HERE,
         base::Bind(&AudioOutputController::OnDeviceChange, controller_));
   }