am 6615defd: Make sure the OMX callback thread is properly shutdown after the node goes away.

Merge commit '6615defd4b8ae627e7f0bbb2382c4d86481f76bd' into gingerbread-plus-aosp

* commit '6615defd4b8ae627e7f0bbb2382c4d86481f76bd':
  Make sure the OMX callback thread is properly shutdown after the node goes away.