We want to know how good are our autofill picks. From https://bugzilla.mozilla.org/show_bug.cgi?id=1474755#c10 As a raw idea, I'd add 2 probes, to be measured only in profiles where autofill is enabled: 1. number of times the user picks a non-heuristic match whose url starts with the typed text 2. number of times the user picks a non-heuristic match when the heuristic match was autofill 3. we already have a count of the autofill picks in URLBAR_SELECTED_RESULT_TYPES Comparing these with the global number of picks could give us some estimate of the problem. The second probe would also give us an estimate whether autofilling domains is actually a good idea, since if most users pick something else when we autofill, then maybe we should autofill something else.