> During the current FLoC origin trial, a page will also be included in the calculation if Chrome detects that the page load ads or ads-related resources. (Ad Tagging in Chromium explains how Chrome's ad detection mechanism works.)
Ad tagging? https://chromium.googlesource.com/chromium/src/+/master/docs...
> Ad Tagging works by matching resource requests against a filter list (...) to determine if they’re ad requests. Any requests matching the filter are tagged as ads. Further, requests (and some DOM elements such as iframes) made on behalf of previously tagged scripts are also tagged as ads by the AdTracker. An iframe will be marked as an ad iframe if its url matches the filter list, if tagged script is involved in the creation of the iframe, or if its parent frame is an ad iframe. The main frame of a page will never be tagged as an ad. Any request made within an ad iframe is considered an ad resource request.
I can't find what is included in this filter list, I'm not sure it's open source.
(mandatory disclaimer: I work at Google, not on Chrome nor ads)