2040953 - Flip browser.privatebrowsing.felt-privacy-v1 to true

Status: VERIFIED FIXED

(Firefox :: Private Browsing, task)

Description

[Manuel Bucher [:manuel]]

This has been rolled out via experiment. It is the stale experiment that causes Bug 2040918. Lets also do the pref flip in code. So that if we end the experiment to get the fire button to show up, we keep the felt-privacy redesign.

https://experimenter.services.mozilla.com/nimbus/private-window-visual-refresh-rollout

Comment 1

[Manuel Bucher [:manuel]]

Attachment: Bug 2040953 - Flip browser.privatebrowsing.felt-privacy-v1 to true

Comment 2

[Phabricator Automation]

firefox-beta Uplift Approval Request

• User impact if declined/Reason for urgency: Mitigation for Fire button not appearing alongside ending
  Uplifting this patch make the release rollout of the feature not required anymore.
  This also enables the private browsing newtab pages consistent across all users, including those with rollouts disabled. The nimbus experiment targeted Fx138+, so has been enabled for a long time.
• Code covered by automated testing?: yes
• Fix verified in Nightly?: no
• Needs manual QE testing?: yes
• Steps to reproduce for manual QE testing: 1. open about:config

2. Is browser.privatebrowsing.felt-privacy-v1 set to true?
3. Open new private browsing window. Does the messaging look alright (can provide screenshot)
   When testing for release, also follow the following additional steps:
4. Unenroll from the experiment private-window-visual-refresh-design-change-only
5. Is browser.privatebrowsing.felt-privacy-v1 still true in about:config?

• Risk associated with taking this patch: low
• Explanation of risk level: The pref has been flipped via nimbus for quite some time (since Fx138). This just matches the default pref to the nimbus one.
• String changes made/needed?: n/a
• Is Android affected?: no

Comment 3

[Manuel Bucher [:manuel]]

Attachment: Bug 2040953 - Flip browser.privatebrowsing.felt-privacy-v1 to true

Original Revision: https://phabricator.services.mozilla.com/D301512

Comment 4

[Phabricator Automation]

firefox-release Uplift Approval Request

• User impact if declined/Reason for urgency: Mitigation for Fire button not appearing alongside ending
  Uplifting this patch make the release rollout of the feature not required anymore.
  This also enables the private browsing newtab pages consistent across all users, including those with rollouts disabled. The nimbus experiment targeted Fx138+, so has been enabled for a long time.
• Code covered by automated testing?: yes
• Fix verified in Nightly?: no
• Needs manual QE testing?: yes
• Steps to reproduce for manual QE testing: 1. open about:config

2. Is browser.privatebrowsing.felt-privacy-v1 set to true?
3. Open new private browsing window. Does the messaging look alright (can provide screenshot)
   When testing for release, also follow the following additional steps:
4. Unenroll from the experiment private-window-visual-refresh-design-change-only
5. Is browser.privatebrowsing.felt-privacy-v1 still true in about:config?

• Risk associated with taking this patch: low
• Explanation of risk level: The pref has been flipped via nimbus for quite some time (since Fx138). This just matches the default pref to the nimbus one.
• String changes made/needed?: n/a
• Is Android affected?: no

Comment 5

[Manuel Bucher [:manuel]]

Attachment: Bug 2040953 - Flip browser.privatebrowsing.felt-privacy-v1 to true

Original Revision: https://phabricator.services.mozilla.com/D301512

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/53067349531a
https://hg.mozilla.org/integration/autoland/rev/cc4ad7189b97
Flip browser.privatebrowsing.felt-privacy-v1 to true r=emz

Comment 7

[Manuel Bucher [:manuel]]

Attachment: privatebrowsing-feltprivacy-true-false.png

Attaching screenshot of how the newtab page looks like with felt privacy true (left) and false (right).

Comment 8

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/cc4ad7189b97

Comment 10

[Ryan VanderMeulen [:RyanVM]]

https://hg-edge.mozilla.org/releases/mozilla-beta/rev/824fa819e6a993dc65279d1860b824a94ac7d945

Comment 11

[Daniel Holbert [:dholbert]]

Note that this pref-flip causes a brief visual regression when opening new Private Browsing windows/tabs (which I just filed as bug 2041470 when I encountered this new design for the first time today, in my main Nightly browsing profile).

I don't know whether that regression is relevant for the uplift consideration, though (it might not really matter), because it seems the pref-flip has already reached release via Nimbus (per comment 0 which links to an experiment with 100% as the population-percentage). So it may be the case that release users are already affected by bug 2041470 (& have been affected for some time), via the nimbus-imposed pref-flip. And in that case, the uplift (just formalizing the pref-flip) clearly doesn't add any additional risk/regression.

Comment 12

[Manuel Bucher [:manuel]]

I currently think we should hold this uplift from release, until bug 2041470 is resolved. And perhaps not uplift to release at all, but let it ride the train with Fx152, but will discuss with team.

Comment 13

[Monica Chiorean]

I was able to reproduce the issue on Win11x64 using FF build 152.0a1(20260512212623) (pref 'browser.privatebrowsing.felt-privacy-v1' is set to false).
Verified on Win11x64 using FF build 153.0a1(20260521211559) that pref is enabled by default ('browser.privatebrowsing.felt-privacy-v1'= true) and remains to true after rolling out of experiment.
Pending verification on next beta build, as current 152.0b1 does not have the fix.

Comment 14

[Monica Chiorean]

Verified as fixed on Win11x64 using FF build 152.0b2(20260522090425), pref is enabled by default.