Use a shared thread for media operations.

webkit/media/webmediaplayer_params.cc

Index: webkit/media/webmediaplayer_params.cc
diff --git a/webkit/media/webmediaplayer_params.cc b/webkit/media/webmediaplayer_params.cc
index 6f013b6176502cd59232408fd4fad7c8237586f1..4c0f74eeae13d698af3b027e984dfb80867d307c 100644
--- a/webkit/media/webmediaplayer_params.cc
+++ b/webkit/media/webmediaplayer_params.cc
@@ -4,18 +4,22 @@
 
 #include "webkit/media/webmediaplayer_params.h"
 
+#include "base/message_loop_proxy.h"
 #include "media/base/audio_renderer_sink.h"
 #include "media/base/media_log.h"
 
 namespace webkit_media {
 
 WebMediaPlayerParams::WebMediaPlayerParams(
+    const scoped_refptr<base::MessageLoopProxy>& message_loop_proxy,
     const scoped_refptr<media::AudioRendererSink>& audio_renderer_sink,
     const scoped_refptr<media::GpuVideoDecoder::Factories>& gpu_factories,
     const scoped_refptr<media::MediaLog>& media_log)
-    : audio_renderer_sink_(audio_renderer_sink),
+    : message_loop_proxy_(message_loop_proxy),
+      audio_renderer_sink_(audio_renderer_sink),
       gpu_factories_(gpu_factories),
       media_log_(media_log) {
+  DCHECK(message_loop_proxy);
   DCHECK(media_log_);
 }