Add browsingContext.historyUpdated event

[OrKoN]

This change adds browsingContext.historyUpdated event to notify the client when a history update happens.

Issue: #502
HTML spec: whatwg/html#10587

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Preview | Diff

[whimboo]

Thank you Alex for getting started on this event! For now I have two questions. See inline.

[sadym-chromium]

LGTM

[juliandescottes]

Thanks, I feel like we should at least have the context info in the event payload, otherwise it will be hard to use?

[OrKoN]

Thanks, I feel like we should at least have the context info in the event payload, otherwise it will be hard to use?

thanks for reviewing, totally! It was a while since I started this PR draft 😅

[juliandescottes]

Thanks for the update, looks good to me!

[jgraham]

A couple of comments, but no blockers.

[jgraham]

I know we don't have this for the other events, but it could be useful to have some informative text indicating that this is only fired for pushState and friends, not for history updates caused by navigation.

[jgraham]

I wonder if we should also include a string indicating the type of the history update to distinguish pushState from replaceState?

[OrKoN]

I think we could add it eventually. So far we didn't expose it and didn't have a use case for it so adding it would involve extra implementation work. Also we could add the serialized history state to be able to distinguish multiple updates if there are use cases.

[OrKoN]

Thanks for reviews! I plan to publish the HTML spec change for review and start working on WPT in the next weeks. For now, I will leave the PR open to incorporate potential updates during the implementation or WPT authoring.

[OrKoN]

Draft WPT tests: web-platform-tests/wpt#48347 I am still clarifying some details on the HTML spec PR.

[OrKoN]

There have been additional discussions on the HTML spec PR resulting in the call being moved to a different place in the HTML spec. PTAL and let me know if you have concerns about it.