Revert of Revert of Always post buffering state updates since they may change sink state.

media/renderers/video_renderer_impl.cc

Index: media/renderers/video_renderer_impl.cc
diff --git a/media/renderers/video_renderer_impl.cc b/media/renderers/video_renderer_impl.cc
index 507599d890ba1613e62b04d0f23742dd4ff5d761..3477db688009006a2526c99ce5817df0d46afb81 100644
--- a/media/renderers/video_renderer_impl.cc
+++ b/media/renderers/video_renderer_impl.cc
@@ -171,8 +171,12 @@
   // failed.
   init_cb_ = BindToCurrentLoop(init_cb);
 
+  // Always post |buffering_state_cb_| because it may otherwise invoke reentrant
+  // calls to OnTimeStateChanged() under lock, which can deadlock the compositor
+  // and media threads.
+  buffering_state_cb_ = BindToCurrentLoop(buffering_state_cb);
+
   statistics_cb_ = statistics_cb;
-  buffering_state_cb_ = buffering_state_cb;
   paint_cb_ = base::Bind(&VideoRendererSink::PaintFrameUsingOldRenderingPath,
                          base::Unretained(sink_));
   ended_cb_ = ended_cb;