GitLab

+ Add support for ripple color on borderless button
+ Refactor out background drawable logic to another class

Bug: 849126, 856244
Change-Id: I5960714129110bea0b9d284779f71592d90e4a36
Reviewed-on: https://chromium-review.googlesource.com/c/1293172Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Becky Zhou <huayinz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601756}