Use enum instead of string in MessageLoopFactory::GetMessageLoop*

media/tools/player_x11/player_x11.cc

Index: media/tools/player_x11/player_x11.cc
diff --git a/media/tools/player_x11/player_x11.cc b/media/tools/player_x11/player_x11.cc
index 85f3fb6779b8b3dfbce5bcd091f6c14c9ea78fea..791469715d80de0000dd31b7a3313a2d9f52d7d1 100644
--- a/media/tools/player_x11/player_x11.cc
+++ b/media/tools/player_x11/player_x11.cc
@@ -118,11 +118,11 @@ bool InitPipeline(MessageLoop* message_loop,
   collection->AddAudioDecoder(new media::FFmpegAudioDecoder(
       base::Bind(&media::MessageLoopFactory::GetMessageLoop,
                  base::Unretained(message_loop_factory),
-                 "AudioDecoderThread")));
+                 media::MessageLoopFactory::AUDIO_DECODER)));
   collection->AddVideoDecoder(new media::FFmpegVideoDecoder(
       base::Bind(&media::MessageLoopFactory::GetMessageLoop,
                  base::Unretained(message_loop_factory),
-                 "VideoDecoderThread"),
+                 media::MessageLoopFactory::VIDEO_DECODER),
       NULL));
 
   // Create our video renderer and save a reference to it for painting.