code: function _onRegistryDownloaded() {
          var availableUpdates = ExtensionManager.getAvailableUpdates();
          PreferencesManager.setViewState("extensionUpdateInfo", availableUpdates);
          PreferencesManager.setViewState("lastExtensionRegistryCheckTime", (new Date()).getTime());
          $("#toolbar-extension-manager").toggleClass("updatesAvailable", availableUpdates.length > 0);
      }
docs: Calculate state of notification everytime registries are downloaded - no matter who triggered the download