When we collect the default browser telemetry in the WDBA, we only collect it if it matches one of the browsers that we already know about. I believe that this is the correct way to go about this, for a couple of reasons. Maybe a company uses something designed in-house that sets a distinct string here. Maybe some niche browser puts the path to the installation as part of this string and, in the event that the user doesn't install with administrator privileges, they do what we do and install into the user directory resulting in us potentially collecting a username in this telemetry.

But I see that we didn't take this same approach when collecting the PDF default in the WDBA. We should fix that. Assuming that the default matches a known default, we probably want to send exactly the same string that we would have otherwise so that we don't cause a telemetry discontinuity.