You don't need cookies to track user activity across the web. If Google is using Etags for example for handling the caching of their web fonts, and if the user

You don't need cookies to track user activity across the web. If Google is using Etags for example for handling the caching of their web fonts, and if the user doesn't have the referer headers disabled, then Google can see who is visiting which page and when. There are other ways to achieve this too