Expose pushManager on Navigator

[marcoscaceres]

Part of https://github.com/w3c/push-api/issues/360

This PR introduces:

• navigator.pushManager
• makes changes to the various method/algorithms of pushManager to distinguish between service worker scope and running in a regular window.

Discussion (or stuff I'm not super happy with):

• Using the "environment settings object" is probably not the best here, because Workers are also an environment (or have an environment settings object).

The current spec is currently hand-wavy about how push registrations are persistently associated with a service worker (which is ok), but not it gets a little bit messier because we need to distinguish between the Window object associated registration and the service worker ones.

Anyone got any suggestions as to what I could use to hand the registration off instead?

The following tasks have been completed:

• [ ] Modified Web platform tests (link to pull request)

Implementation commitment:

• [ ] Chromium (https://bugs.chromium.org/p/chromium/issues/detail?id=)
• [ ] Gecko (https://bugzilla.mozilla.org/show_bug.cgi?id=)
• [ ] WebKit (https://bugs.webkit.org/show_bug.cgi?id=)

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Preview | Diff

[marcoscaceres]

Actually, thinking about this... if an (main thread) origin (i.e., "a site") has a persistent environment settings object, and service worker has its own independently persistent environment-settings object, then we could say that every environment has an associated push subscription (which can be null).

This could work because:

• a service worker can has at most 1 push subscription
• a window would have at most 1 push subscription.

Tying subscription to the environment then that could answer how push subscriptions are associated with execution contexts.

[martinthomson]

Thanks for writing this up Marcos. I'm going to probably step aside on this one and defer to @saschanaz. Both of us are about to go on some leave, so I hope you don't mind if this takes a little while.

[marcoscaceres]

No problem at all. I'll put up a few PRs over xmas and try to keep them small.

I talked to Anne about using "environment", but he suggested they are too volatile... so, I'm going to create some kind of persistent "push subscriptions store" instead. That will be just simple store that handles the association between push subscriptions, service workers, and the origin.

[saschanaz]

Some early thought:

I talked to Anne about using "environment", but he suggested they are too volatile... so, I'm going to create some kind of persistent "push subscriptions store" instead. That will be just simple store that handles the association between push subscriptions, service workers, and the origin.

Perhaps we can associate push manager to storage bottle as Web Locks does for lock managers?: https://w3c.github.io/web-locks/#lock-managers