This is an extension protocol that can be used for platform specific
API (ie. AccessibleWrap methods).
I'm not thrilled with the seperate constructor for the sub-protocol.
This means that the parent won't have the actor upon DocAccessibleParent
construction, and some timing bugs can arise because of the extra round
trip. It would be cool if both actors could be co-created, but that
would require ManagedEndpoint, and for PBrowser to manage them both. I
don't want to expose this to PBrowser.
Differential Revision: https://phabricator.services.mozilla.com/D37955
--HG--
extra : moz-landing-system : lando
