GitLab

- Setup the tile group manager component.
- Implemented the load, save and get APIs.
- Added unittests.

- [UPDATED] Have a big update since initial reviews.

Bug: 1068368
Change-Id: I03ebf98f9c67af403d355418cb1304f161bb28e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2138161
Auto-Submit: Hesen Zhang <hesen@chromium.org>
Commit-Queue: Hesen Zhang <hesen@chromium.org>
Reviewed-by: Shakti Sahu <shaktisahu@chromium.org>
Reviewed-by: Xing Liu <xingliu@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Cr-Commit-Position: refs/heads/master@{#761153}