GitLab

Implementing custom caption bar as there will likely be motion specs
requiring unique animation.

Close button not currently wired up.
Demo in bug.

Also fixed a height issue with DialogPlate.

Bug: b:79440488
Change-Id: I6eecff9c48c231e1b1d8aaea026baca09979b7ca
Reviewed-on: https://chromium-review.googlesource.com/1062185Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Commit-Queue: David Black <dmblack@google.com>
Cr-Commit-Position: refs/heads/master@{#559369}