[gdm] legacy-display: ensure X server is dead when respawning

[Ray Strode <halfline src gnome org>]

commit 7f08535cbcb73697d151dde8fa113ed08d0b4175
Author: Ray Strode <rstrode redhat com>
Date:   Wed Jul 12 10:26:37 2017 -0400

    legacy-display: ensure X server is dead when respawning
    
    If the user logs out we may detect the session dying before
    we detect the X server dying.  If that happens, then we
    currently don't wait for the X server to exit before starting
    a new X server.
    
    This commit makes sure to explicitly kill the X server and wait
    for its death before proceeding.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=788786

 daemon/gdm-legacy-display.c |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)
---
diff --git a/daemon/gdm-legacy-display.c b/daemon/gdm-legacy-display.c
index 9c99923..d9c4336 100644
--- a/daemon/gdm-legacy-display.c
+++ b/daemon/gdm-legacy-display.c
@@ -263,10 +263,31 @@ gdm_legacy_display_class_init (GdmLegacyDisplayClass *klass)
 }
 
 static void
+on_display_status_changed (GdmLegacyDisplay *self)
+{
+        int status;
+
+        status = gdm_display_get_status (self);
+
+        switch (status) {
+            case GDM_DISPLAY_UNMANAGED:
+                if (self->priv->server != NULL)
+                        gdm_server_stop (self->priv->server);
+                break;
+            default:
+                break;
+        }
+}
+
+static void
 gdm_legacy_display_init (GdmLegacyDisplay *legacy_display)
 {
 
         legacy_display->priv = GDM_LEGACY_DISPLAY_GET_PRIVATE (legacy_display);
+
+        g_signal_connect (legacy_display, "notify::status",
+                          G_CALLBACK (on_display_status_changed),
+                          NULL);
 }
 
 GdmDisplay *