As shown in the previous commits, synchronous search is easily implemented
by the asynchronous search API. The only reason we still have a
synchronous search API is of historical reasons. Well, we're not a museum,
and git log can keep our fossils safe if need be....
https://bugzilla.gnome.org/show_bug.cgi?id=675328
Allow applications to register search providers by dropping a keyfile
into a well-known directory. For now, initialize all found providers;
long term, we probably want to give users the ability to restrict the
set of active search providers.
https://bugzilla.gnome.org/show_bug.cgi?id=663125
Add an asynchronous search provider for results from a DBus service
implementing the org.gnome.Shell.SearchProvider interface; this
will allow applications to hook into the Shell's search without
implementing it in Shell itself or requiring an extension.
https://bugzilla.gnome.org/show_bug.cgi?id=663125
