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 27c8a218665d7856a3ebb0b0b1ecb4acc45d413e..82826b7c8020d8fd0cc446ee20c607808c27688b 100644
--- a/webkit/media/webmediaplayer_impl.cc
+++ b/webkit/media/webmediaplayer_impl.cc
@@ -176,6 +176,7 @@ WebMediaPlayerImpl::WebMediaPlayerImpl(
   // Create default video renderer.
   scoped_refptr<media::VideoRendererBase> video_renderer =
       new media::VideoRendererBase(
+          pipeline_message_loop,
           base::Bind(&WebMediaPlayerProxy::Repaint, proxy_),
           BIND_TO_RENDER_LOOP(&WebMediaPlayerImpl::SetOpaque),
           true);