GitLab

- Remove flag for account wallet.
- Add API for users to give consent.
- Change CWVSyncControllerDataSource to be class property so that
  the sync/auth stack will be able to ask for tokens during setup.
- Add method to CWVSyncControllerDataSource to return all accounts.
  This is required by chromium to maintain the freshness of tokens.
- Clear all local data when sync stops until we can handle data
  migration situations.
- Simplify CWVSyncControllerDelegate's did stop sync method.

Change-Id: I1773c270958ecffa21aa5196c94c1510bc7084a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1816641
Commit-Queue: John Wu <jzw@chromium.org>
Reviewed-by: Hiroshi Ichikawa <ichikawa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#699944}