GitLab

This builds off of DialogPlate motion spec part 1:
https://chromium-review.googlesource.com/c/chromium/src/+/1137843

This CL:
- Fixes issue which caused settings to fade in/out. Previously we used
  two settings buttons, now we use a single button which exists outside
  of the layout containers being animated.
- Implements translation phase of the animation.

See bug for spec/demo.

Bug: b:111500701
Change-Id: I269666dafa815018e0cf65df299aa734eaf80b79
Reviewed-on: https://chromium-review.googlesource.com/1139031
Commit-Queue: David Black <dmblack@google.com>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575901}