services: desktop: Deprecate 'accountsservice-service' procedure.

* doc/guix.texi (Desktop Services): Replace 'accountsservice-service'
with 'accountsservice-service-type'.
* gnu/services/desktop.scm (accountsservice-service): Deprecate procedure.
(desktop-services-for-system): Use accountsservice-service-type.
* gnu/tests/lightdm.scm (minimal-desktop-services): Ditto.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

doc/guix.texi

@@ -23428,18 +23428,17 @@ Data type representing the configuration of @command{elogind}.
 @end table
 @end deftp
 
-@deffn {Scheme Procedure} accountsservice-service @
-       [#:accountsservice @var{accountsservice}]
-Return a service that runs AccountsService, a system service that can
+@defvar accountsservice-service-type
+Type for the service that runs AccountsService, a system service that can
 list available accounts, change their passwords, and so on.
 AccountsService integrates with PolicyKit to enable unprivileged users
 to acquire the capability to modify their system configuration.
-@uref{https://www.freedesktop.org/wiki/Software/AccountsService/, the
-accountsservice web site} for more information.
+See @url{https://www.freedesktop.org/wiki/Software/AccountsService/,
+AccountsService} for more information.
 
-The @var{accountsservice} keyword argument is the @code{accountsservice}
-package to expose as a service.
-@end deffn
+The value for this service is a file-like object, by default it is
+set to @code{accountsservice} (the package object for AccountsService).
+@end defvar
 
 @deffn {Scheme Procedure} polkit-service @
                          [#:polkit @var{polkit}]

gnu/services/desktop.scm

@@ -126,7 +126,7 @@
             fontconfig-file-system-service
 
             accountsservice-service-type
-            accountsservice-service
+            accountsservice-service  ; deprecated
 
             cups-pk-helper-service-type
             sane-service-type
@@ -1295,7 +1295,9 @@ over D-Bus that can list available accounts, change their passwords, and so
 on.  AccountsService integrates with PolicyKit to enable unprivileged users to
 acquire the capability to modify their system configuration.")))
 
-(define* (accountsservice-service #:key (accountsservice accountsservice))
+(define-deprecated
+  (accountsservice-service #:key (accountsservice accountsservice))
+  accountsservice-service-type
   "Return a service that runs AccountsService, a system service that
 can list available accounts, change their passwords, and so on.
 AccountsService integrates with PolicyKit to enable unprivileged users to
@@ -1858,7 +1860,7 @@ applications needing access to be root.")
          (service avahi-service-type)
          (udisks-service)
          (service upower-service-type)
-         (accountsservice-service)
+         (service accountsservice-service-type)
          (service cups-pk-helper-service-type)
          (service colord-service-type)
          (geoclue-service)

gnu/tests/lightdm.scm

@@ -46,7 +46,7 @@
 (define minimal-desktop-services
   (list polkit-wheel-service
         (service upower-service-type)
-        (accountsservice-service)
+        (service accountsservice-service-type)
         (service polkit-service-type)
         (service elogind-service-type)
         (dbus-service)