Created attachment 218730 [details] [review]
WIP patch to migrate to libsecret

libsecret is a new client for the Secret Service DBus API. The Secret Service
allows storage of passwords in a common way on the desktop. Supported by
gnome-keyring and ksecretservice.

libsecret solves many problems with libgnome-keyring. Relevant to
vino: it solves threading issues, uses GDBus instead of dbus-glib.

A future GNOME goal will be to migrate away from libgnome-keyring to libsecret:

https://live.gnome.org/GnomeGoals/LibsecretMigration

I've done a rough WIP patch in order to make sure that the libsecret API
covered all the use cases. I'll attach that patch here. I hope the patch is a
help for the migration, but I don't plan to iterate on it at the current time.

Some notes about the patch:

 * Ideally vino would use its own password schema, and not use 
   SECRET_SCHEMA_COMPAT_NETWORK (which is the successor of
   gnome_keyring_set_network_password() and friends). By using its own
   password schema seahorse and other applications can better identify
   the passwords that vino stores. But of course changing isn't so simple
   as it would break for already stored passwords.
 * I haven't tested the patch. I'm not familiar with how to trigger all the
   various code paths and logic.