GitLab

According to go/chrome-bmo design doc sync data model,
we should have two copies of app's name and theme_color fields.

Rename specifics to sync_data.
Rename proto to local_data.

Add is_sync_placeholder flag.

Add comments.

All these fields will be used in WebAppSyncBridge implementation:
https://chromium-review.googlesource.com/c/chromium/src/+/1830494

Bug: 860583
Change-Id: Idce95b5fdd4843cf9a8e290fe61293bffb938bc5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1833347
Commit-Queue: Alexey Baskakov <loyso@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Reviewed-by: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702713}