Add local logs to TelephonyBackupAgent.

These will give some insight into what happened on the last
restore attempt which should be helpful in case of SMS restore
related issues. This info will be available even after device
is rebooted.

Test: manual
Bug: 164211717
Change-Id: Ia37f3020953dc3bca6d59deac52069a14cdd78e5
1 file changed