Bug 1453699 covers the problem that Legacy LocalStorage does not work (acceptably) with a "network.cookie.lifetimePolicy" of ACCEPT_SESSION (2) due to data never being notionally persisted, resulting in new processes always starting from a clean-ish state. (Technically they see any durable state from before the preference was set to ACCEPT_SESSION, which is weird and nothing anyone would ever expect.)

:dragana made the excellent suggestion that since we're not quite yet ready to pref on LSNG for everyone, we could at least cause the ACCEPT_SESSION lifetime policy to enable LSNG.

We may also want a secondary failsafe preference that allows opting out of this such that the logic is:

• LSNG is enabled if:
  • OR:
    • dom.storage.next_gen is true
    • network.cookie.lifetimePolicy is 2 and dom.storage.next_gen_as_needed is (default) true. The latter pref might be something that doesn't have to go in StaticPrefList.yaml and only just be checked as a one-off pref API check in NextGenLocalStorageEnabled, but this probably deserves some thought.

Fortunately, the changes in D77846 didn't land, so we can just extend NextGenLocalStorageEnabled as Andrew pointed out.

https://hg.mozilla.org/mozilla-central/rev/7b892adceb3f

Hey,
I am the student worker from the anti-tracking team, I am working on deprecating and removing the network.cookie.lifetimePolicy. The Shutdown cleaning will be controlled solely by privacy.sanitize.sanaitizeOnShutdown. I am now in the process of tracking down the network.cookie.lifetimePolicy and removing it. Since the network.cookie.lifetimePolicy will not be used anymore, can this LSNG check just be removed as well or do I need a workaround? Happy about any input.

(In reply to hpeuckmann@mozilla.com from comment #5)

Hey,
I am the student worker from the anti-tracking team, I am working on deprecating and removing the network.cookie.lifetimePolicy. The Shutdown cleaning will be controlled solely by privacy.sanitize.sanaitizeOnShutdown. I am now in the process of tracking down the network.cookie.lifetimePolicy and removing it. Since the network.cookie.lifetimePolicy will not be used anymore, can this LSNG check just be removed as well or do I need a workaround? Happy about any input.

Resolved via slack, thanks Jan.