[gnome-control-center] power: Fix crash when panel is closed quickly

[Bastien Nocera <hadess src gnome org>]

commit 1d72a0b3507d425011a4d280ebbe53f3463d3ed9
Author: Benjamin Berg <bberg redhat com>
Date:   Mon Mar 5 16:12:48 2018 +0100

    power: Fix crash when panel is closed quickly
    
    Fix a use-after-free while creating the dbus proxy for
    org.gnome.SettingsDaemon.Power.Keyboard. This fix is identical to the
    previous fix for the screen proxy.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=794089

 panels/power/cc-power-panel.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)
---
diff --git a/panels/power/cc-power-panel.c b/panels/power/cc-power-panel.c
index aff0ae8e6..f9b67a458 100644
--- a/panels/power/cc-power-panel.c
+++ b/panels/power/cc-power-panel.c
@@ -1117,11 +1117,11 @@ static void
 got_kbd_proxy_cb (GObject *source_object, GAsyncResult *res, gpointer user_data)
 {
   GError *error = NULL;
-  CcPowerPanel *self = CC_POWER_PANEL (user_data);
-  CcPowerPanelPrivate *priv = self->priv;
+  CcPowerPanel *self;
+  GDBusProxy *kbd_proxy;
 
-  priv->kbd_proxy = g_dbus_proxy_new_for_bus_finish (res, &error);
-  if (priv->kbd_proxy == NULL)
+  kbd_proxy = g_dbus_proxy_new_for_bus_finish (res, &error);
+  if (kbd_proxy == NULL)
     {
       if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
         g_printerr ("Error creating keyboard proxy: %s\n", error->message);
@@ -1129,8 +1129,11 @@ got_kbd_proxy_cb (GObject *source_object, GAsyncResult *res, gpointer user_data)
       return;
     }
 
+  self = CC_POWER_PANEL (user_data);
+  self->priv->kbd_proxy = kbd_proxy;
+
   /* we want to change the bar if the user presses brightness buttons */
-  g_signal_connect (priv->kbd_proxy, "g-properties-changed",
+  g_signal_connect (kbd_proxy, "g-properties-changed",
                     G_CALLBACK (on_kbd_property_change), self);
 
   sync_kbd_brightness (self);