[Start Surface] Add toolbar animations

Screen capture:
https://drive.google.com/drive/folders/1VSZGz0yMwmYBV0uG0Zv5jgtLzKQt8DVM?usp=sharing

Bug: 1025296
Change-Id: I6d3671252578fa9f37e5f1173b8d55b364a898c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1981853
Commit-Queue: Mia Glaese <glamia@chromium.org>
Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Reviewed-by: Patrick Noland <pnoland@chromium.org>
Reviewed-by: Ganggui Tang <gogerald@chromium.org>
Cr-Commit-Position: refs/heads/master@{#741772}
12 files changed