Create video and audio decoder threads on demand.

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 b2e7acc4f74343c2c9fa69b6af7fabcefd67a5dc..00f7e4d2bc23e39b31b2a28821015dbd65970e43 100644
--- a/media/tools/player_wtl/movie.cc
+++ b/media/tools/player_wtl/movie.cc
@@ -80,9 +80,9 @@ bool Movie::Open(const wchar_t* url, VideoRendererBase* video_renderer) {
   collection->SetDemuxerFactory(scoped_ptr<DemuxerFactory>(
       new FFmpegDemuxerFactory(data_source, pipeline_loop)));
   collection->AddAudioDecoder(new FFmpegAudioDecoder(
-      message_loop_factory_->GetMessageLoop("AudioDecoderThread")));
+      message_loop_factory_.get(), "AudioDecoderThread"));
   collection->AddVideoDecoder(new FFmpegVideoDecoder(
-      message_loop_factory_->GetMessageLoop("VideoDecoderThread")));
+      message_loop_factory_.get(), "VideoDecoderThread"));
 
   // TODO(vrk): Re-enabled audio. (crbug.com/112159)
   collection->AddAudioRenderer(new media::NullAudioRenderer());