This adds a new `advance_screens` pseudo-action to the `feature_callout`
messaging system template, which can be added to any action in the same
way `navigate` is used currently. This should generally be used instead
of `navigate`, which only advances the inner content but not the outer
wrapper, the anchor, the page event listeners, and other state relevant
for panel callouts.
Some callouts want to show even if the `cfr.features` pref is disabled,
such as surveys and important onboarding messages, and hard-coding that
check in FeatureCallout is heavy-handed as we already have better ways
to do it. Most callouts belong to the `cfr` group, which locks them
behind the features pref. Any that can't use groups, like the PDF
annotations callouts, can check the pref directly in their targeting.
Aside from blocking messages that don't want to be blocked by that pref,
it also results in a weird behavior where, if the pref changes while the
callout is still open (pretty unlikely), the callout will hide when you
click "next" instead of advancing to the next screen. If you clicked the
Next button, it should show you the next screen, even if you somehow
blocked the message by pref before clicking.
So it's cleaner to just let ASRouter handle that in the targeting phase.
If the pref changes while a message is showing, then we'll just leave it
open, and it won't apply until targeting is checked.
It's appropriate to make the change here, because this patch adds a new
screen advancement scheme, separate from the tour pref system. Since
we're reproducing the advancement logic, we're forced to decide whether
to reproduce the feature pref check in this new scheme. I realized 99%
of the time it's doing nothing, and in the rare cases where it does have
an effect that differs from the regular pref targeting, it's a negative
effect. And at that point, we might as well rip the bandaid off all at
once, to keep everything consistent.
Additionally, while adding documentation for this new feature, I also
corrected some existing errors in the documentation.
Differential Revision: https://phabricator.services.mozilla.com/D229084
68848bd409