Changes

== Opt-out Doorhanger Infobar ==

[[File:DoH CFRDoH_Infobar.png|frameless|DoH CFR message Infobar screenshot]]* When the client is first enrolled in the rollout, we show a doorhanger an infobar popup to let the user know that DoH is available.* This doorhanger infobar offers an option to opt-out, which results in permanently disabling heuristics and other mechanisms.* The doorhanger infobar is shown only if the rollout is "successful" - i.e. the user did not already have custom DoH preferences or active enterprise policy.* The doorhanger infobar is implemented as a CFR message, gated behind the relevant prefs.