[iOS][MF] Change buttons to look like chips

Changes the aspect of the buttons in Manual Fallback to be like chips.
Slides and more info in crbug.com/942001

Bug: 942002, 942001
Change-Id: I6fa86fc6f2abae6ded4f1f177efdf411c6ac8a03
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1529284
Commit-Queue: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Reviewed-by: David Jean <djean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#642450}
12 files changed