The background update agent will use an ephemeral profile, it will be deleted when the agent exits. Even so we would like to reduce the amount of file I/O the agent generates by disabling writing things to the profile where possible.

The cookie service always creates a cookies database in the profile regardless of whether any networking occurs but it also has a private mode that functions without the database so this bug will add a way to always use that mode and not create the database at all when running in the background.

Background tasks run with a temporary profile and we want to reduce disk I/O by
stopping things from writing to the profile where doing so is straightforward.
Since the cookie service already supports in-memory storage for private browsing
we can easily disable the persistent storage when running a background task.

Note that this depends on the patch in https://phabricator.services.mozilla.com/D96481.

Background tasks run with a temporary profile and we want to reduce disk I/O by
stopping things from writing to the profile where doing so is straightforward.
Since the cookie service already supports in-memory storage for private browsing
we can easily disable the persistent storage when running a background task.

I'm not working on this, Nick is this still needed or can it just be closed?

(In reply to Dave Townsend [:mossop] (Out May 3-14) from comment #3)

I'm not working on this, Nick is this still needed or can it just be closed?

It is still a nice to have; it'll show up more as we get to Bug 1679443.

Firefox background tasks use a new temporary profile directory for
every invocation. We would like to write as little data as possible
into the temporary profile directory in this mode. This patch allows
to make the persistent cookie storage discard cookies just like
private cookie storage.

This approach simply uses that the base CookieStorage class is close
to sufficient already. There may be a performance impact with more
virtual invocations, but none of these functions seem likely to be
hot.

NI to baku to answer https://phabricator.services.mozilla.com/D139910#inline-773464 and suggest a docstring.

Depends on D139910

https://hg.mozilla.org/mozilla-central/rev/09bb73dac836
https://hg.mozilla.org/mozilla-central/rev/51c22199741b