Use enum instead of string in MessageLoopFactory::GetMessageLoop*

media/filters/ffmpeg_audio_decoder_unittest.cc

Index: media/filters/ffmpeg_audio_decoder_unittest.cc
diff --git a/media/filters/ffmpeg_audio_decoder_unittest.cc b/media/filters/ffmpeg_audio_decoder_unittest.cc
index ae5b82c0774e08129e2075db0bd7137be1366c6a..cac6e8a2b56083c8e14ca685b451420e798ac5af 100644
--- a/media/filters/ffmpeg_audio_decoder_unittest.cc
+++ b/media/filters/ffmpeg_audio_decoder_unittest.cc
@@ -30,8 +30,9 @@ ACTION_P(InvokeReadPacket, test) {
 class FFmpegAudioDecoderTest : public testing::Test {
  public:
   FFmpegAudioDecoderTest()
-      : decoder_(new FFmpegAudioDecoder(base::Bind(&Identity<MessageLoop*>,
-                                                   &message_loop_))),
+      : decoder_(new FFmpegAudioDecoder(base::Bind(
+            &Identity<scoped_refptr<base::MessageLoopProxy> >,
+            message_loop_.message_loop_proxy()))),
         demuxer_(new StrictMock<MockDemuxerStream>()) {
     CHECK(FFmpegGlue::GetInstance());