I neglected to test beyond "Glean and GleanPings are available in privileged about contexts" and thus missed that no instrumentation APIs actually work. Trying e.g. Glean.aCategory.aName.record() returns Permission denied for <%2$S> to create wrapper for object of class %1$S.

Nika explains that XPCOM-wrapped JS isn't allowed in content contexts, regardless of privilege. So it seems as though we're going to have to go full webidl to make this work:

• Move dom/chrome-webidl/ interfaces to dom/webidl/ and replace [ChromeOnly] with [Func="nsGlobalWindowInner::IsGleanNeeded"]
• Move interfaces out of t/c/g/xpcom/nsIGleanMetrics.idl to webidl/, rewriting to webidl (no more AUTF8String. Learn to love DOMString. And drop those nsI prefixes. And nsISupports is now any or object.)
• Reimplement moved interfaces in new headers that you reference in dom/bindings/Bindings.conf
• Basically follow https://firefox-source-docs.mozilla.org/dom/webIdlBindings/index.html and see what happens.

It'd be nice if we could do this piecemeal, starting with only supporting Event since that's the interesting one, but I'm getting a sinking feeling that we'll have to convert this all in one go.

Since we're exposing Glean types in not-chrome-only contexts like privileged
"about:" pages, we can't live in chrome-webidl/ any longer.

Depends on D186266

ni?nika -- Is https://phabricator.services.mozilla.com/D186267 about right? I'm specifically wondering how much of my cargo cult is needed (can I just... drop? nsISupports? if we're not doing XPCOMish things?), whether my hunch about using metrics' WrapObject to generate the JSObject for Category and Labeled's NamedGetters are in the right ballpark, whether I'm safe to return nullptr from GetParentObject (and, if not, how I should think about "parent" here).

All in all, I've been finding the docs to be a lovely resource. I just want to make sure I'm not completely off course before I take care of the rest of the interfaces.

Clearing the ni? as I've left some comments.

The severity field is not set for this bug.
:chutten, could you have a look please?

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Sorry, bugbug, I forgot that one.

Since I'm here, might as well supply an update. I'm working through review comments, hoping to have a new version up for reviewers early-mid next week. Other things, like setting fires in the woods (camping. I was camping for three days), keep taking priority but this is still on my desk.

chutten: it looks like this patch does not impact Glean metric generation in a way that would directly impact Bug 1852098. Can you confirm? Thanks!

Correct. The scope of this problem is limited to JS modules in non-Chrome contexts, and Use Counters are managed entirely within C++.

Depends on D186267

Not sure this is the ideal semantics, but it appeases some tests that depend on
the behaviour.

Depends on D187812

Depends on D187813

Also: add a missing await for testClickResultTelemetry and,
since this is a multiprocess test, ensure we always wait for FOG IPC to flush
before clearing data.

Depends on D187937

Depends on D187938

Backed out for bustages on TimingDistribution.cpp

Backout link: https://hg.mozilla.org/integration/autoland/rev/1105d2849f18b5435e9333a0a66d820178af01f0
Log link: https://treeherder.mozilla.org/logviewer?job_id=429686709&repo=autoland&lineNumber=64640

Ah, non-unified builds are Tier 1 now. Lemme tighten up these includes and try another local build before I resubmit.

https://hg.mozilla.org/mozilla-central/rev/a88fa44abdc9
https://hg.mozilla.org/mozilla-central/rev/b5f79a977cd5
https://hg.mozilla.org/mozilla-central/rev/87d76dd03552
https://hg.mozilla.org/mozilla-central/rev/074f9e36e8a0
https://hg.mozilla.org/mozilla-central/rev/e2c9789f7de1
https://hg.mozilla.org/mozilla-central/rev/7369ca94287c
https://hg.mozilla.org/mozilla-central/rev/d63842cc4cf9