After fixing this, it would be a good idea to go through all of the histograms we own and add browser tests if there isn't one. 

Dug around a bit and found that felt@ deprecated this histogram intentionally in https://codereview.chromium.org/1317593002 because most of the values aren't useful for non-overrideable interstitials (like the bad clock one). Unfortunately I don't see a way to mark this histogram as deprecated in histograms.xml because of the way it's defined with histogram_suffixes.

If it's deprecated, can we remove it? What's the replacement histogram? (it's not immediately clear to me from the CL)