Route zoom value through to zoomIndex in device API

Current UI is wired to track zoom index, so pass that in rather
than the unfinished new zoom ratio API. This finishes the fix for
zoom in the app.

Extended TODO already there. App should continue to operate until
one big refactor moves it form working with zoom indices, to working
with zoom ratios, no breakage in between.

Bug: 16527845
Change-Id: I8d88c3d34ba9ad85b1a115cf1249548a16722a38
1 file changed