title: Android: Task or application equivalent of onPause
body: <p>My application uses a remote service to play audio.  I do this so that
  no activity owns the playback of the audio - the user can trigger some
  audio to be played from one Activity, and the audio will continue to
  play as they navigate around the app.  I do, however, want to tell the
  service to pause or stop playing audio when the user "unloads" the app
  either by backing out, locking the display, or hitting Home.  When the app was a single
  activity, I was doing this in onPause.  So, I guess I'm essentially
  looking for "onPause" at the application/task level.  Does such thing
  exist?  If not, what is the "best practice" way of getting notified
  that the task has been put on hold by the user either backing all the
  way out or hitting Home?</p>