Add Declarative Web Push

[annevk]

This introduces a new feature whereby push messages conforming to a certain JSON format directly create an end user notification and show it (possibly preceded by an enhanced push event).

This builds on whatwg/notifications#213 which adds URL members to notifications.

Exposing PushManager outside of service workers is #393.

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The following tasks have been completed:

• Modified Web platform tests (link to pull request): IDL will be tested, but otherwise there's no good infrastructure for this as-of-yet.

Implementer support:

• Chromium (has indicated support at times)
• Gecko
• WebKit

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Preview | Diff

[martinthomson]

I'd like to see more explanatory text attached to this sort of change. (In the spec, not the PR, for avoidance of doubt.)

From what I can see, a message is opportunistically parsed as JSON. If it parses and there is a "web_push": 9001 (?!) attribute, the browser attempts to make a notification. If that works, the notification is shown.

There is also a mutable attribute attached, which would allow the SW the option of intercepting the notification and tweaking it before it is shown. That would somewhat negate the benefits from a purely declarative notification, so it seems an unnecessary feature (the app could save the "web_push": 9001 bytes and just make a notification for itself).

[saschanaz]

Can we split mutable out of this PR for now?

[saschanaz]

Mostly fine with a few changes. We explicitly did not cover the app badge part of this PR though.

[saschanaz]

This happens after "If |registration| is not found, abort these steps." step above. Either #393 or this PR should fix that.

[annevk]

I would suggest we fix that in #393. And we merge this first.

[saschanaz]

wfm.

[saschanaz]

Force push breaks "Changes since your last review" feature 😵

[annevk]

I made 7551a5f and a64358c before I squashed (to create the copy PR for app badge). Both super tiny commits. Removal of app badge is a separate commit again.

[saschanaz]

You can check Mozilla on the interest list. (Or well, I did)

[saschanaz]

Looking at WebKit/WebKit#18087, it seems WebKit shipped "pushnotification" event instead of reusing existing "push" event, deviating from this PR? 🤔

(Edit: Or WebKit changed it to "push" but the remnant of "pushnotification" is still in the source?)

Filed https://bugs.webkit.org/show_bug.cgi?id=296772

[saschanaz]

Also WebKit considers mutable as a member of notification instead of a member of the top level push message.

Filed https://bugs.webkit.org/show_bug.cgi?id=296770.

[annevk]

Thanks for finding those bugs, we'll get them fixed!