am 160edb36: Add ability to guard a thread against setting its own prio to bg

Merge commit '160edb3645f8b7012bab70ae6e6e8c4a5733082b' into gingerbread-plus-aosp

* commit '160edb3645f8b7012bab70ae6e6e8c4a5733082b':
  Add ability to guard a thread against setting its own prio to bg