These methods were initially introduced when I was planning on having
an explicit DisableExtension/EnableExtension, instead of hooking up
a gsettings notify. This behavior was changed at the last minute, but
the methods were kept to avoid having to change the browser-plugin.
Consumers of this API should just set the GSettings key directly
instead now.
https://bugzilla.gnome.org/show_bug.cgi?id=676837
12c7cc278d