Canonicalize notification channel sounds for backup
Canonicalize for backup and canonicalize and uncanonicalize for restore
(see comment).
Test: Set custom notification sound, make backup, remove notification
sound from device (from Ringtones and make sure to update media content
provider), restore => Observe default instead of random number. Do the
same without removing the sound and observe restores successfully.
Test: runtest systemui-notification
Bug:
66444697
(cherry picked from commit
c27bb6ad34fd59161f6460b692ba72c7ede789b6)
Change-Id: I32c186d0d7479b01f6cc67cce9bc5cb66264a064