Pass in media message loop to VideoRendererBase and enforce calling on the right thread.

webkit/media/webmediaplayer_impl.cc

Index: webkit/media/webmediaplayer_impl.cc
diff --git a/webkit/media/webmediaplayer_impl.cc b/webkit/media/webmediaplayer_impl.cc
index c02e3db281ce72add1f63e4d87bf0393934089e5..68ed3bdd1250e2d0eb2bf153c466e0c188ac8fa1 100644
--- a/webkit/media/webmediaplayer_impl.cc
+++ b/webkit/media/webmediaplayer_impl.cc
@@ -184,7 +184,8 @@ WebMediaPlayerImpl::WebMediaPlayerImpl(
       new media::VideoRendererBase(
           base::Bind(&WebMediaPlayerProxy::Repaint, proxy_),
           BIND_TO_RENDER_LOOP(&WebMediaPlayerImpl::SetOpaque),
-          true);
+          true,
+          pipeline_message_loop);
   filter_collection_->AddVideoRenderer(video_renderer);
   proxy_->set_frame_provider(video_renderer);