* Enabling Chrome Sync, which is opt-in
* Syncing history, which is on by default if you enable sync
* Not using a custom passphrase for sync data (not using one is the default)
* Having "My Activity" save "Web & App activity", which is opt-out
* Having synced Chrome history data sent to "Web & App activity", which is opt-out
For the last two bullets, the opt-outs are at https://myaccount.google.com/activitycontrols .