fune/browser/components/asrouter/README.md

Activity Stream Router

Preferences browser.newtab.activity-stream.asrouter.*

Name	Used for	Type	Example value
allowHosts	Allow a host in order to fetch messages from its endpoint	[String]	["gist.github.com", "gist.githubusercontent.com", "localhost:8000"]
providers.cfr	Message provider options for cfr	Object	see below
providers.onboarding	Message provider options for onboarding	Object	see below
useRemoteL10n	Controls whether to use the remote Fluent files for l10n, default as true	Boolean	`[true

Message providers examples

{
  "id" : "onboarding",
  "enabled": true,
  "type" : "local",
  "localProvider" : "OnboardingMessageProvider"
}

Message format documentation