Google Dashboard has a new section for package tracking. If you scroll down to the package tracking section, you'll probably see this information: "Package tracking data is accessible (e.g. in Google Now and Google Wallet)." Expand the section and you'll see a button that lets you opt out: "By clicking the button you will opt out of Package Tracking in various Google applications and data will be removed. You can opt in again via Google Wallet or Google Now."
I'm not sure why package tracking is singled out and Google doesn't let you disable from Google Dashboard the other features that use data from Gmail.