- reduces number of "modes" to just two: normal and wide
- consolidate the normal/narrow modes for phone and tablet (as per spec)
with the only diff on the tablet being side paddings
- fix issue with "white arrow" visual being shown in phone when tapping
on a message
- make touch computations be resilient to padding values instead of
assuming that the check/star icons are right at the left/right
Bug: 5103823
Change-Id: I23f967454f7744d9c59256625e302e54a353994a
