[gnome-control-center] background: Remove some dead code

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 4838ce4228d975ff42f8e01fc8bbf382ee80df42
Author: Florian Müllner <fmuellner gnome org>
Date:   Tue Feb 11 15:15:26 2020 +0100

    background: Remove some dead code
    
    update_preview() is never called with a non-NULL item.
    
    https://gitlab.gnome.org/GNOME/gnome-control-center/issues/864

 panels/background/cc-background-panel.c | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)
---
diff --git a/panels/background/cc-background-panel.c b/panels/background/cc-background-panel.c
index 51b082c32..27efe88b0 100644
--- a/panels/background/cc-background-panel.c
+++ b/panels/background/cc-background-panel.c
@@ -82,24 +82,12 @@ get_current_background (CcBackgroundPanel *panel,
 
 static void
 update_preview (CcBackgroundPanel *panel,
-                GSettings         *settings,
-                CcBackgroundItem  *item)
+                GSettings         *settings)
 {
   CcBackgroundItem *current_background;
 
   current_background = get_current_background (panel, settings);
 
-  if (item && current_background)
-    {
-      g_object_unref (current_background);
-      current_background = cc_background_item_copy (item);
-      if (settings == panel->settings)
-        panel->current_background = current_background;
-      else
-        panel->current_lock_background = current_background;
-      cc_background_item_load (current_background, NULL);
-    }
-
   if (settings == panel->settings)
     cc_background_preview_set_item (panel->desktop_preview, current_background);
   else
@@ -337,7 +325,7 @@ on_settings_changed (GSettings         *settings,
                      CcBackgroundPanel *panel)
 {
   reload_current_bg (panel, settings);
-  update_preview (panel, settings, NULL);
+  update_preview (panel, settings);
 }
 
 static void
@@ -359,9 +347,9 @@ cc_background_panel_init (CcBackgroundPanel *panel)
 
   /* Load the backgrounds */
   reload_current_bg (panel, panel->settings);
-  update_preview (panel, panel->settings, NULL);
+  update_preview (panel, panel->settings);
   reload_current_bg (panel, panel->lock_settings);
-  update_preview (panel, panel->lock_settings, NULL);
+  update_preview (panel, panel->lock_settings);
 
   /* Background settings */
   g_signal_connect (panel->settings, "changed", G_CALLBACK (on_settings_changed), panel);