Collapse app bar while doing search in app page

Prior to this cl, user can see a large space on app bar
while user is doing search on app bar.

In this cl, we enforce to collapse the tool bar in
search case, and we don't allow user can scroll app bar as well.

Fix: 187016306
Test: Play around the search behavior in app page.
Change-Id: I25ba3ef24949cc43989fec4a80f75a24a8d92c07