FWIW, the initial versions of Chrome did not have Google as the default search provider - the first run experience had a dialog that made you choose between the top three search engines in your locale
The search engine choice screen in Android did have a bid model (and complicated EU regulation around it), but the search engine choice screen in the early versions of Chrome were not a bid model - we just felt it was a cool thing to do, but we removed it because practically everyone chose Google anyway and first run screens are bad for retention.
Google later even refused to say what the competitors were paying for that rank, so they probably just overbid themselves for a while now.
Note that they do this for Android, too.