Update the app-specific picker to have a container like the main picker

This is to ensure widgets are displayed with same container across the
two pickers.

* http://screencast/cast/NDYxNjMzNDExNjY1MTAwOHwwMTBlYzkwZC0wNg
* http://screencast/cast/NjY1NzAyNzY5NzgwMzI2NHwyYTg3ZWIzNS0wNw
* http://screencast/cast/NTYyMzcwMTc4NDQ5NDA4MHw3Y2JlZDEwZS04Mw

Bug: 328812171
Flag: N/A
Test: Manual - need to build a SS test for this opened - 336284716
Change-Id: I42b743b99cf6f47b7bade57de01b130df78ac1e9