Navigation bar size scaling (1 of 2)

Summary:
Largest is stock, down to rather slim. Navigation bar width, for
devices that have "navigationBarCanMove", the sizes are kept
reasonably proportionate to stock values, without getting
excessively small.

Depends on D436

Change-Id: I82f5c27a0088f389bdda217b5976b3ec4fae219c

Test Plan: give it a go

Reviewers: synergy

Reviewed By: synergy

Differential Revision: http://review.codefirex.com/D438