1961268 - Add co-enrolling messagingSystem nimbus feature

Status: NEW

(Firefox :: Messaging System, task, P3)

Description

[Shane Hughes [:aminomancer]]

Bug 1874939 adds experiment co-enrollment, which means we don't need a bunch of fxms-message-* features. We can maintain just one feature for ASRouter, and enable co-enrollment for it, so any number of experiments can contribute data on the same feature id. We'll need to maintain the existing features just until they no longer have any active deployments.

This will mean you can no longer turn off a deployment in a given cohort by rolling out an empty experiment on the same feature id, so we might want to provide better tools for no-opping messages. Right now you can sorta do it by shipping a dummy message with no content but the same targeting/trigger/etc. But there are cases where this doesn't work so well, where that dummy message ends up disabling more messages than you intended because there were multiple messages whose footprints overlap. So it would be better if we just allowed a special disable_message template that basically instructed ASRouter to disable a message with the specified id.

This bug can include both the initial feature (added to the manifest) and the disable_message template. But then we should file a followup, dependent on this bug, for eventually removing all the other messaging features that don't have specialized parameters. That should be most of them, i.e. all the messaging features that just feed into ASRouter without any special schema.