Minor restore fixes

1. We were missing a 'break' in the session-timeout case of
   message dispatch, so were falling through into a different
   case.  Oops.  Fortunately it was benign; the other case's
   logic was merely logging "hey it doesn't look like there's
   anything to do here" and cleanly exiting.

2. After a restore operation finishes we were previously
   always leaving the session timeout clock running.  However,
   this was not appropriate in the case of restore-at-install,
   when the restore was a one-shot kicked off by the package
   manager rather than an operation on an ongoing RestoreSession.
   That logic now properly tidies up the session timeout when
   winding up the restore in either situation.

Bug 17080648

Change-Id: I51d4a50db4feefc4c355230a3bfb926ea2fb5944