Calls NavManager.update() when we starts/closes search.

NavManager.update() automatically handles the case in which if search
bar is expanded, title is null'd out.

Piggy-backing SearchManagerListener and added additional interface to
make sure #update gets called, along with sortmodel update.

Bug: 30372436
Change-Id: I9a5ae1601648d7c0680dfaff181bf3c8156e3114