Run |demuxer_| related tasks in the media thread in GTV.

content/renderer/media/android/webmediaplayer_android.cc

Index: content/renderer/media/android/webmediaplayer_android.cc
diff --git a/content/renderer/media/android/webmediaplayer_android.cc b/content/renderer/media/android/webmediaplayer_android.cc
index ec0565e3b3c75258a9d77068165ffafd19ab60f3..f8eea96504bf4453bd55891ac09988d01dcd8b95 100644
--- a/content/renderer/media/android/webmediaplayer_android.cc
+++ b/content/renderer/media/android/webmediaplayer_android.cc
@@ -65,12 +65,14 @@ WebMediaPlayerAndroid::WebMediaPlayerAndroid(
     RendererMediaPlayerManager* manager,
     WebMediaPlayerProxyAndroid* proxy,
     StreamTextureFactory* factory,
+    const scoped_refptr<base::MessageLoopProxy>& media_loop,
     media::MediaLog* media_log)
     : frame_(frame),
       client_(client),
       delegate_(delegate),
       buffered_(1u),
       main_loop_(base::MessageLoopProxy::current()),
+      media_loop_(media_loop),
       ignore_metadata_duration_change_(false),
       pending_seek_(0),
       seeking_(false),
@@ -230,7 +232,7 @@ void WebMediaPlayerAndroid::load(LoadType load_type,
   if (source_type_ != MediaPlayerAndroid::SOURCE_TYPE_URL) {
     has_media_info_ = true;
     media_source_delegate_.reset(
-        new MediaSourceDelegate(proxy_, player_id_, media_log_));
+        new MediaSourceDelegate(proxy_, player_id_, media_loop_, media_log_));
     // |media_source_delegate_| is owned, so Unretained() is safe here.
     if (source_type_ == MediaPlayerAndroid::SOURCE_TYPE_MSE) {
       media_source_delegate_->InitializeMediaSource(