fix CAB mode not working when launched from widget/notification

Restoring a conversation selection set caused the Controller
observer to be lost.

Bonus: fixed parts of save/restore of selection set, although I
couldn't get this fully working due to b/6268401.

Bug: 6247729
Change-Id: Ic11a2390d9efbac50f9d76067d616cd4aafc0db0
2 files changed