Use enum instead of string in MessageLoopFactory::GetMessageLoop*

media/tools/player_wtl/movie.cc

Index: media/tools/player_wtl/movie.cc
diff --git a/media/tools/player_wtl/movie.cc b/media/tools/player_wtl/movie.cc
index eb117badd867748a60237b1dea184631d0bc2801..32a7c1f24bfc70cebbe6e6104dc7a4cab8201081 100644
--- a/media/tools/player_wtl/movie.cc
+++ b/media/tools/player_wtl/movie.cc
@@ -60,7 +60,8 @@ bool Movie::Open(const wchar_t* url, VideoRendererBase* video_renderer) {
   message_loop_factory_.reset(new media::MessageLoopFactory());
 
   MessageLoop* pipeline_loop =
-      message_loop_factory_->GetMessageLoop("PipelineThread");
+      message_loop_factory_->GetMessageLoop(
+          media::MessageLoopFactory::PIPELINE);
   pipeline_ = new Pipeline(pipeline_loop, new media::MediaLog());
 
   // Open the file.
@@ -76,11 +77,11 @@ bool Movie::Open(const wchar_t* url, VideoRendererBase* video_renderer) {
   collection->AddAudioDecoder(new FFmpegAudioDecoder(
       base::Bind(&MessageLoopFactory::GetMessageLoop,
                  base::Unretained(message_loop_factory_.get()),
-                 "AudioDecoderThread")));
+                 media::MessageLoopFactory::AUDIO_DECODER)));
   collection->AddVideoDecoder(new FFmpegVideoDecoder(
       base::Bind(&MessageLoopFactory::GetMessageLoop,
                  base::Unretained(message_loop_factory_.get()),
-                 "VideoDecoderThread"),
+                 media::MessageLoopFactory::VIDEO_DECODER),
       NULL));
 
   // TODO(vrk): Re-enabled audio. (crbug.com/112159)