Jetpack::plugin_upgrade PHP Method

    function plugin_upgrade()
    {
        if (Jetpack::is_active()) {
            list($version) = explode(':', Jetpack_Options::get_option('version'));
            if (JETPACK__VERSION != $version) {
                // Check which active modules actually exist and remove others from active_modules list
                $unfiltered_modules = Jetpack::get_active_modules();
                $modules = array_filter($unfiltered_modules, array('Jetpack', 'is_module'));
                if (array_diff($unfiltered_modules, $modules)) {
                    Jetpack::update_active_modules($modules);
                }
                add_action('init', array(__CLASS__, 'activate_new_modules'));
                // Upgrade to 4.3.0
                if (Jetpack_Options::get_option('identity_crisis_whitelist')) {
                    Jetpack_Options::delete_option('identity_crisis_whitelist');
                }
                Jetpack::maybe_set_version_option();
            }
        }
    }

 /**
  * Singleton
  * @static
  */
 function init()
 {
     static $instance = false;
     if (!$instance) {
         load_plugin_textdomain('jetpack', false, dirname(plugin_basename(__FILE__)) . '/languages/');
         $instance = new Jetpack();
         $instance->plugin_upgrade();
     }
     return $instance;
 }