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

media/tools/player_x11/player_x11.cc

Index: media/tools/player_x11/player_x11.cc
diff --git a/media/tools/player_x11/player_x11.cc b/media/tools/player_x11/player_x11.cc
index 58222530de1e07ae6a1ec8d7c6bcc35188251b29..42b891fb450e43325678273e158966d21f08724b 100644
--- a/media/tools/player_x11/player_x11.cc
+++ b/media/tools/player_x11/player_x11.cc
@@ -118,6 +118,7 @@ bool InitPipeline(const scoped_refptr<base::MessageLoopProxy>& message_loop,
 
   // Create our video renderer and save a reference to it for painting.
   g_video_renderer = new media::VideoRendererBase(
+      message_loop,
       base::Bind(&Paint, paint_message_loop, paint_cb),
       base::Bind(&SetOpaque),
       true);