I'm guessing this is part of the telemetry Chrome gathers. IIRC when you first install Chrome, there's an opt-in (or opt-out) where it asks the user whether sen

I'm guessing this is part of the telemetry Chrome gathers. IIRC when you first install Chrome, there's an opt-in (or opt-out) where it asks the user whether sending usage information to Google is okay. Firefox does something similar. The total on that page is either the number from their telemetry or an approximation based on those numbers and the size of their user base.