https://support.google.com/accounts/answer/3265955?hl=sv
Survey overlay:
support.google.com##.hs-enabled.hs
I think you might have to be logged into a Google account for the overlay in order to trigger the overlay, by the way.
https://support.google.com/accounts/answer/3265955?hl=sv
support.google.com##.hs-enabled.hs