userMenu: Ignore 'lock-enabled' setting for user switching

The preference controls whether the screen should be locked when
the screensaver is activated, not whether the screen should be
locked at all. In particular after having switched to a different
user, log out should not automatically switch back to the unlocked
session, so always activate the lock when user switching.

https://bugzilla.gnome.org/show_bug.cgi?id=685536

js/ui/userMenu.js

@@ -824,8 +824,7 @@ const UserMenuButton = new Lang.Class({
     _onLoginScreenActivate: function() {
         this.menu.close(BoxPointer.PopupAnimation.NONE);
         Main.overview.hide();
-        if (this._screenSaverSettings.get_boolean(LOCK_ENABLED_KEY))
-            Main.screenShield.lock(false);
+        Main.screenShield.lock(false);
         Gdm.goto_login_session_sync(null);
     },