Add check for "Silent" Uri.EMPTY Ringtone Uri
am: ad54e7f053

* commit 'ad54e7f053f00d6c77fe18c11cc5e7c5a7b8fb60':
  Add check for "Silent" Uri.EMPTY Ringtone Uri

Change-Id: I74143ae1faae397e75cd4de7dbe2302ab2fe629a