Convert ColorChooser away from GridLayout.

Also adds an example for it on the platforms where it's built.

Bug: 1261301
Change-Id: Ib651902ec92c45d10deefbab9af400a8037507a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3383438


Commit-Queue: Peter Kasting <pkasting@chromium.org>
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Allen Bauer <kylixrd@chromium.org>
Commit-Queue: Allen Bauer <kylixrd@chromium.org>
Cr-Commit-Position: refs/heads/main@{#958204}