Disable randomised Firefox HTTP cache decay user test groups

[isis]

I need to look into it more, but I think we should be setting browser.cache.frecency_experiment to -1 to ​disable HTTP_CACHE_MISS_HALFLIFE_EXPERIMENT. Since we have Telemetry disabled, of course, Mozilla's experiment shouldn't be collecting any data on our users. However, if that pref is not set in firefox.js to -1, it will default to 0. And if it's 0, then it's randomised between 1 and 4 inclusive, setting different HTTP cache decay times for the four groups, which might make for a bit of a rough-edged fingerprinting mechanism.

[bugzilla]

Mozilla continues its experiment, now with sub-hour resolution: ​https://bugzilla.mozilla.org/show_bug.cgi?id=1098422

[cypherpunks]

We don't need any experiments active in Tor Browser.

[cypherpunks]

we should be setting browser.cache.frecency_experiment to -1

to fix this ticket without patching.

[gk]

Thanks for contributing. We use needs_review for tickets that have patches attached we can reason about and merge if we think they are okay. I am happy to consider a patch to get this ticket moved forward. So, if you could attach one or point to some commit in a (preferably) git repository that would be great.

[cypherpunks]

Replying to gk:

Thanks for contributing.

Thank you too. We made a great progress for the last several years. So, glad to hear it from you.

We use needs_review for tickets that have patches attached we can reason about and merge if we think they are okay.

needs_review was used to show that thorough code analysis didn't reveal anything wrong with the proposed solution, and it can be merged as is.

I am happy to consider a patch to get this ticket moved forward.

Sure, but no one added it during 3 years, for some reason.

So, if you could attach one or point to some commit in a (preferably) git repository that would be great.

It is so easy that it's better suited as an exercise for new job applicants.

[ffmancera]

Here is a patch, I did the changes in 000-tor-browser.js instead of firefox.js. If it is wrong, please let me know.

[gk]

Thanks, applied to tor-browser-52.6.0esr-8.0-2 (commit f6d6512bf85d964fa5a470f2528042c527523a34).

[cypherpunks]

​https://bugzilla.mozilla.org/show_bug.cgi?id=1430197