1749613 - Allow rolling back TCP rollout

Status: RESOLVED WONTFIX

(Firefox :: Messaging System, enhancement)

Description

[Ed Lee :Mardak]

[Tracking Requested - why for this release]: This might want release 96 or beta 97 uplift depending on how urgent this rollout will happen.

Bug 1732271 originally added a new pref privacy.restrict3rdpartystorage.rollout.enabledByDefault that can be toggled by users through various nimbus-controlled UIs (spotlight message action bug 1738206 and about:preferences bug 1737565) to turn on Total Cookie Protection.

Currently, if the nimbus enrollment/rollout "experiment" is stopped, users who have opted in will still have the user set preference enabling TCP behavior (but won't see the messaging anymore). We want some way to roll users back to pre-TCP behavior.

andreio:

• It seems like we can achieve this by additionally checking for nimbus feature enrollment and/or additionally gating the BrowserGlue behavior to also check NimbusFeatures.tcpPreferences.isEnabled():
  https://searchfox.org/mozilla-central/rev/d107bc8aeadcc816ba85cb21c1a6a1aac1d4ef9f/browser/components/BrowserGlue.jsm#1725-1727

• How were we planning on progressively enrolling more users as I believe we didn't want to have long running "experiments" blocking the spotlight feature?

Comment 1

[Andrei Oprea [:andreio]]

I don't think the nimbus feature check will work, the opt-in action will toggle the TCPToggleInStandard pref which is the fallback pref for tcpPreferences.enabled. Once a user opts in (ENABLE_TOTAL_COOKIE_PROTECTION_SECTION_AND_OPT_OUT), pref is set and isEnabled remains true even if experiment is ended (user pref value will take precedence even if experiment config is "off").

We could have a call for getExperimentMetaData(feature: tcp) where you suggested in BrowserGlue. Or alternatively we could register an tcpPreferences.onUpdate that does clearUserPref when the experiment is turned off.

I think we can enroll more users by using rollouts, they're available in 97.

Comment 2

[Ed Lee :Mardak]

We will favor user choice and accept leaving users who explicitly opted in to TCP as part of the rollout.