Clean up preferences set in configure_firefox.py

[vringar]

A number of prefs we set have been removed for multiple years.
We should investigate how to maintain the functionality we originally used the prefs for.

[palmeida]

Is there a list of the prefs that have been removed? I was curious about this and looked for some in about:config, but then I saw this discussion where someone says browser.pagethumbnails.capturing_disabled - one of those used by OpenWPM that I couldn't find in about:config, - is a hidden pref, so I don't know where to look.

[palmeida]

I started checking the preferences in Firefox's code. The slowStartup ones have simply been removed: https://bugzilla.mozilla.org/show_bug.cgi?id=1690854

[vringar]

Hey @palmeida,
thanks for investigating this.
My first thought would be to use searchfox and paste each pref string in there. This should give you an idea whether the pref still exists.
Would you also want to write a PR to remove the prefs or would you rather post the results of your investigation here?

[palmeida]

Hi @vringar ,

I could do the PR, especially for the simple ones that were just removed and don't provide any useful functionality. If there are some that need to be replaced with new preferences I don't know if I'll be able to do it (I can try).

In any case, I can add a comment here with the results of my investigation and go from there. I have been using searchfox now.

One doubt I have is whether the string existing in the code is enough to keep it or should functionality be tested. For instance, if "browser.rights.3.shown" were to be removed, would that affect OpenWPM audits? Of course the easiest path is to start by removing/adapting the preferences that don't exist anymore.

[vringar]

Thank you for putting time into this!

Don't stress too much about reimplementing the functionality that has been lost over time.
Cleaning up and documenting what needs to be reimplemented is valuable in itself.

As for ambiguous prefs, I'd just keep them for now and focus on clear cut cases. Once that is done, we can create new issues for the ambiguous prefs and split up that work.

[vringar]

@palmeida Hey, do you have any WIP branch that I could pick up?
I might have some time for the next couple of weeks, and might do this.

[palmeida]

@palmeida Hey, do you have any WIP branch that I could pick up? I might have some time for the next couple of weeks, and might do this.

Sorry, I haven't had any time to look into it since November. I'm still working on a project that uses OpenWPM, so I might go back to this, but I've been busy with other issues.