[gdm] display: add back manage vfunc

[Ray Strode <halfline src gnome org>]

commit 8b2ac7e7ac11165187c8314f8c20efec18305863
Author: Ray Strode <rstrode redhat com>
Date:   Wed Feb 4 10:28:38 2015 -0500

    display: add back manage vfunc
    
    This function will be overridden by GdmLocalDisplay to
    start the X server.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=744764

 daemon/gdm-display.c |   11 ++++++++++-
 daemon/gdm-display.h |    3 ++-
 2 files changed, 12 insertions(+), 2 deletions(-)
---
diff --git a/daemon/gdm-display.c b/daemon/gdm-display.c
index 7b06a9d..f8674c4 100644
--- a/daemon/gdm-display.c
+++ b/daemon/gdm-display.c
@@ -626,6 +626,12 @@ on_slave_started (GdmSlave   *slave,
         _gdm_display_set_status (self, GDM_DISPLAY_MANAGED);
 }
 
+static void
+gdm_display_real_manage (GdmDisplay *self)
+{
+        gdm_slave_start (self->priv->slave);
+}
+
 static gboolean
 gdm_display_real_prepare (GdmDisplay *self)
 {
@@ -674,7 +680,9 @@ on_list_cached_users_complete (GObject       *proxy,
                 g_variant_unref (call_result);
         }
 
-        gdm_slave_start (self->priv->slave);
+        if (GDM_DISPLAY_GET_CLASS (self)->manage != NULL) {
+                GDM_DISPLAY_GET_CLASS (self)->manage (self);
+        }
 }
 
 static void
@@ -1390,6 +1398,7 @@ gdm_display_class_init (GdmDisplayClass *klass)
         object_class->finalize = gdm_display_finalize;
 
         klass->prepare = gdm_display_real_prepare;
+        klass->manage = gdm_display_real_manage;
 
         g_object_class_install_property (object_class,
                                          PROP_ID,
diff --git a/daemon/gdm-display.h b/daemon/gdm-display.h
index 39976b9..b3685ee 100644
--- a/daemon/gdm-display.h
+++ b/daemon/gdm-display.h
@@ -56,7 +56,8 @@ typedef struct
         GObjectClass   parent_class;
 
         /* methods */
-        gboolean (*prepare)                   (GdmDisplay *display);
+        gboolean (*prepare) (GdmDisplay *display);
+        void     (*manage)  (GdmDisplay *self);
 } GdmDisplayClass;
 
 typedef enum