With the previous cleanups, these fields aren't needed any longer.
We can also clean up some unused methods and simplify existing code.

BUG=angle:466

Change-Id: I96df8d152324bda5e6868b5eccdf52bdc09155e9
Reviewed-on: https://chromium-review.googlesource.com/207256Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Nicolas Capens <capn@chromium.org>