Put Users First team is working on TBMv2 ads metrics. These metrics will use the layout tree snapshots in traces to find ads' sizes and positions. The positions can be compared with the viewport to find when the ads are on-screen.

Currently, the layout tree snapshots indicate every layout object's size, position, and type, so we can find iframes and their sizes, but we can't tell if those iframes are ads.

Catapult has a list of a few known ad networks domains, so if TracedLayoutObject traced the 'src' attribute for iframe LayoutObjects, then catapult would be able to tell which iframes are ads.