Don't always consume user activation for close watchers

[domenic]

trafficstars

Closes #10046.

• [ ] At least two implementers are interested (and none opposed):
  • Chromium
  • @zcorpan or @lukewarlow, able to speak for Gecko or WebKit on this one?
• [ ] Tests are written and can be reviewed and commented upon at:
  • TODO
• [x] Implementation bugs are filed:
  • Chromium: https://bugs.chromium.org/p/chromium/issues/detail?id=1512224
  • Gecko: https://bugzilla.mozilla.org/show_bug.cgi?id=1859702 (general close request/close watcher bug)
  • WebKit: https://bugs.webkit.org/show_bug.cgi?id=263305 (general close request/close watcher bug)
  • Deno (only for timers, structured clone, base64 utils, channel messaging, module resolution, web workers, and web storage): N/A
  • Node.js (only for timers, structured clone, base64 utils, channel messaging, and module resolution): N/A
• [x] MDN issue is filed: Not necessary for this edge-case change
• [x] The top of this comment includes a clear commit message to use.

(See WHATWG Working Mode: Changes for more details.)

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/interaction.html ( diff )

[lukewarlow]

I'm implementing this in WebKit in a personal capacity there's no official standards position from WebKit yet.

[lukewarlow]

Fwiw this change makes sense to me

[zcorpan]

My understanding is that this is bug fix to make CloseWatcher work as intended. OK for Mozilla.

[josepharhar]

https://github.com/web-platform-tests/wpt/pull/44024

[domenic]

Implementing this in Chromium has uncovered some significant bugs in the anti-abuse logic of close watchers. The new proposed spec allows infinite back-trapping, and the existing spec didn't have enough test coverage. A more significant overhaul will be needed. I think I have something almost working...

[lukewarlow]

@domenic is there a PR for your overhaul so I can take a look through it? Just wondering how much I'll need to change the draft WebKit implementation

[domenic]

I have a work in progress Chromium CL. This version is passing all the tests but is ugly bad code; this version is my attempt at refactoring but it's now failing some of the tests, so we shouldn't trust it yet. But, it can give you an idea of what I expect the changes to look like:

• More first-class tracking of close watcher groups, instead of using "is grouped with previous" / "created with user activation".
• Tracking the amount of allowed groups, in a way that increments / decrements at appropriate points in time.
• Using those to figure out (a) when creating a new close watcher, whether it goes into the topmost existing group or a new group; (b) whether we can fire the cancel event.

[domenic]

Superseded by https://github.com/whatwg/html/pull/10168; any review over there is appreciated!