Add new Fragment API for explicitly saving/restoring state.

Also fix issue #4519821:
Blank screen displayed on tapping "Battery Use" option in the settings

We weren't correctly doing the full Activity resume code when coming
back from delivering a new Intent or result.

And fix a fragment problem where we still weren't correctly restoring
the state of list views.  (I think this was from a bad manual-merge
from master.)

Change-Id: If79dc7e998155c39ab8c04781f6c73a82238a9ef