Refactor accessibility focus rings

This is a pure refactor, with no functional change.

Bug: 955783
Change-Id: I3c88bbda768f5ac863c7994e75a3c2a92ceca366
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1583443
Commit-Queue: Anastasia Helfinstein <anastasi@google.com>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654129}
3 files changed