am 37b939a6: Merge change 7395 into donut

Merge commit '37b939a63742c9a0cea4e6982bfb0581def45d6d'

* commit '37b939a63742c9a0cea4e6982bfb0581def45d6d':
  Move the silent ringtone to ringtones/notifications, so it can be used for both.