GitLab

Trying to make things clearer with the following renames:

- Start -> OnSyncStarting
- FinishStart -> ReadyToConnect
- OnConnect -> ConnectSync
- Stop -> DisconnectSync

BUG=584486

Review URL: https://codereview.chromium.org/1671773002

Cr-Commit-Position: refs/heads/master@{#374842}