I filed bugs[1][2] on other engines, there's explicit support from 
Chromium on this[3], and the relevant spec[4] and WPT[5] changes are up 
for review, so as soon as they're merged I plan to turn the pref on on 
all platforms.
The bug for this is 
https://bugzilla.mozilla.org/show_bug.cgi?id=1685675
Let me know if there's any concerns with this. Florian in the CSSWG call 
raised a potential fingerprinting issue[6], but:
  * As discussed in that call that's a more general issue with 
autofilling. I think we never autofill without user interaction, too, 
which mitigates this.
  * It is already observable on Gecko via CSS (because we use the 
pseudo-class in the user-agent stylesheet, so you can query it by its 
effects like changing the computed values of color / filter).
Cheers,
  -- Emilio
[1]: 
https://bugs.chromium.org/p/chromium/issues/detail?id=1164311
[2]: 
https://bugs.webkit.org/show_bug.cgi?id=220459
[3]: 
https://github.com/whatwg/html/issues/6181#issuecomment-735665906
[4]: 
https://github.com/whatwg/html/pull/6273
[5]: 
https://github.com/web-platform-tests/wpt/pull/27098
[6]: 
https://github.com/w3c/csswg-drafts/issues/5775#issuecomment-755793947
On 12/10/20 3:20 AM, Emilio Cobos Álvarez wrote:
> Summary:
> 
> I plan to prototype a standard :autofill pseudo-class, for two reasons
> 
>   * We have an internal :-moz-autofill pseudo-class, and webkit-based 
> browsers have a publicly-exposed :-webkit-autofill counter-part.
>   * We have a fair amount of compat reports of people forgetting 
> :-webkit-autofill is not standard and making unrelated CSS not apply to 
> Firefox.
> 
> Thus, I think it'd be nice to have an unprefixed pseudo-class authors 
> can use, and parse the :-webkit- prefix (unfortunately) for compat.
> 
> Bug: 
https://bugzilla.mozilla.org/show_bug.cgi?id=1475316
> 
> Standards: 
https://github.com/whatwg/html/issues/6181 and 
> 
https://github.com/w3c/csswg-drafts/issues/5775 for the relevant spec 
> discussion where I hope to get consensus.
> 
> Pref: layout.css.autofill.enabled.
> 
> Devtools Bug: I don't think devtools needs particular support. We could 
> add an :autofill checkbox to the pseudo-classes submenu, please file and 
> ni? me if you think it'd be useful.
> 
> Other browsers: Both WebKit and Blink ship for a long time prefixed 
> (:-webkit-autofill)
> 
> web-platform-tests: I'll add parsing tests once the spec discussion is 
> done. We can't do much more because actual autofill behavior is not 
> particularly standard.
> _______________________________________________
> dev-platform mailing list
> 
dev-pl...@lists.mozilla.org
> 
https://lists.mozilla.org/listinfo/dev-platform