1967328 - Create a Nimbus feature for session restore with variable for controlling whether the session restore is ON by default

Status: RESOLVED FIXED

(Firefox :: Session Restore, enhancement, P1)

Description

[Ania]

We want to experiment with offering session restore being ON by default for new users.

The Nimbus feature could be:
sessionRestore
description: A feature that controls the default state of the session restore.

And the variable could be:
sessionRestoreEnabled
type: boolean
setPref:
branch: user
pref: unsure if there's an existing pref
description: True if the session restore is ON ("Open previous windows and tabs" in about:preferences).

The variable should persist after the experiment it is used in has ended.

Comment 1

[Sam Foster [:sfoster] (he/him)]

The pref to control this behavior is browser.startup.page. It has a few possible integer values:

• 0: blank (start with only a blank tab)
• 1: home (load whatever the value of browser.startup.homepage) is in a tab. This is the default value.
• 2: load last visited page
• 3: resume previous browser session.

This same pref has UI in about:preferences as the "Open previous windows and tabs" checkbox. Checking the box sets the pref to 3. Un-checking resets it to 1.

The population we want to target is when the user has not set browser.startup.page (i.e. matches preferenceIsUserSet) and its value is the default value of 1. But, if the user gets enrolled in the experiment and uses about:config or the preferences UI to revert the pref, we need a way to unenroll them from the experiment. Using the preferenceIsUserSet filter expression should prevent re-enrolling them at that point.

Comment 2

[Sam Foster [:sfoster] (he/him)]

Attachment: Bug 1967328 - Add a sessionRestore feature and startupBehavior variable for experimenting with enabling session restore by default. r?beth

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/f6f8c88f45aa
https://hg.mozilla.org/integration/autoland/rev/a2d1a9c6d3d9
Add a sessionRestore feature and startupBehavior variable for experimenting with enabling session restore by default. r=beth

Comment 4

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/a2d1a9c6d3d9

Comment 5

[Sam Foster [:sfoster] (he/him)]

Attachment: Bug 1967328 - Add a sessionRestore feature and startupBehavior variable for experimenting with enabling session restore by default. r?beth

Original Revision: https://phabricator.services.mozilla.com/D257305

Comment 6

[Phabricator Automation]

firefox-beta Uplift Approval Request

• User impact if declined: (none) Planned experiment in 142 will not be possible
• Code covered by automated testing: yes
• Fix verified in Nightly: no
• Needs manual QE test: no
• Steps to reproduce for manual QE testing: None
• Risk associated with taking this patch: Low
• Explanation of risk level: The patch just adds a new nimbus feature and variable
• String changes made/needed: None
• Is Android affected?: no

Comment 7

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/808aafafe0c7
https://hg.mozilla.org/releases/mozilla-beta/rev/a291be5da206