prefs: Remove live-hidden-windows preference

The preference existed, even though it was hard-coded to true. Just
remove it for good.

https://bugzilla.gnome.org/show_bug.cgi?id=671104

src/core/prefs.c

@@ -53,7 +53,6 @@
 #define KEY_GNOME_CURSOR_SIZE "cursor-size"
 
 #define KEY_OVERLAY_KEY "overlay-key"
-#define KEY_LIVE_HIDDEN_WINDOWS "live-hidden-windows"
 #define KEY_WORKSPACES_ONLY_ON_PRIMARY "workspaces-only-on-primary"
 #define KEY_NO_TAB_POPUP "no-tab-popup"
 
@@ -104,7 +103,6 @@ static MetaButtonLayout button_layout;
 /* NULL-terminated array */
 static char **workspace_names = NULL;
 
-static gboolean live_hidden_windows = FALSE;
 static gboolean workspaces_only_on_primary = FALSE;
 
 static gboolean no_tab_popup = FALSE;
@@ -345,13 +343,6 @@ static MetaBoolPreference preferences_bool[] =
       },
       &edge_tiling,
     },
-    {
-      { KEY_LIVE_HIDDEN_WINDOWS,
-        SCHEMA_MUTTER,
-        META_PREF_LIVE_HIDDEN_WINDOWS,
-      },
-      &live_hidden_windows,
-    },
     {
       { "workspaces-only-on-primary",
         SCHEMA_MUTTER,
@@ -1613,9 +1604,6 @@ meta_preference_to_string (MetaPreference pref)
     case META_PREF_FORCE_FULLSCREEN:
       return "FORCE_FULLSCREEN";
 
-    case META_PREF_LIVE_HIDDEN_WINDOWS:
-      return "LIVE_HIDDEN_WINDOWS";
-
     case META_PREF_WORKSPACES_ONLY_ON_PRIMARY:
       return "WORKSPACES_ONLY_ON_PRIMARY";
 
@@ -2127,27 +2115,6 @@ meta_prefs_get_force_fullscreen (void)
   return force_fullscreen;
 }
 
-gboolean
-meta_prefs_get_live_hidden_windows (void)
-{
-#if 0
-  return live_hidden_windows;
-#else
-  return TRUE;
-#endif
-}
-
-void
-meta_prefs_set_live_hidden_windows (gboolean whether)
-{
-  MetaBasePreference *pref;
-
-  find_pref (preferences_bool, sizeof(MetaBoolPreference),
-             KEY_LIVE_HIDDEN_WINDOWS, &pref);
-  g_settings_set_boolean (SETTINGS (pref->schema), KEY_LIVE_HIDDEN_WINDOWS,
-                          whether);
-}
-
 gboolean
 meta_prefs_get_workspaces_only_on_primary (void)
 {