Settings: Don't crash if we pause too quickly

Notifier is unregistered in every case in pause.
However, if you close the Settings app too quick, the notifier
might not be registered at all, causing an IllegalArgumentException
during the unregistering.

Change-Id: I54141cbfc91d08c28ef524f4155b673ae8dee90e
Settings: Quick Record Tile (2/2)

Signed-off-by: Arnav Gosain <nolinuxnoparty@gmail.com>
Settings: Port SmoothProgressBar: User Custom ProgressBar Setting [1/2] + OmniSwitch
Settings: Audio Themes Settings (2/3)