WC_Install::background_installer PHP Method

    public static function background_installer($plugin_to_install_id, $plugin_to_install)
    {
        if (!empty($plugin_to_install['repo-slug'])) {
            require_once ABSPATH . 'wp-admin/includes/file.php';
            require_once ABSPATH . 'wp-admin/includes/plugin-install.php';
            require_once ABSPATH . 'wp-admin/includes/class-wp-upgrader.php';
            require_once ABSPATH . 'wp-admin/includes/plugin.php';
            WP_Filesystem();
            $skin = new Automatic_Upgrader_Skin();
            $upgrader = new WP_Upgrader($skin);
            $installed_plugins = array_map(array(__CLASS__, 'format_plugin_slug'), array_keys(get_plugins()));
            $plugin_slug = $plugin_to_install['repo-slug'];
            $plugin = $plugin_slug . '/' . $plugin_slug . '.php';
            $installed = false;
            $activate = false;
            // See if the plugin is installed already
            if (in_array($plugin_to_install['repo-slug'], $installed_plugins)) {
                $installed = true;
                $activate = !is_plugin_active($plugin);
            }
            // Install this thing!
            if (!$installed) {
                // Suppress feedback
                ob_start();
                try {
                    $plugin_information = plugins_api('plugin_information', array('slug' => $plugin_to_install['repo-slug'], 'fields' => array('short_description' => false, 'sections' => false, 'requires' => false, 'rating' => false, 'ratings' => false, 'downloaded' => false, 'last_updated' => false, 'added' => false, 'tags' => false, 'homepage' => false, 'donate_link' => false, 'author_profile' => false, 'author' => false)));
                    if (is_wp_error($plugin_information)) {
                        throw new Exception($plugin_information->get_error_message());
                    }
                    $package = $plugin_information->download_link;
                    $download = $upgrader->download_package($package);
                    if (is_wp_error($download)) {
                        throw new Exception($download->get_error_message());
                    }
                    $working_dir = $upgrader->unpack_package($download, true);
                    if (is_wp_error($working_dir)) {
                        throw new Exception($working_dir->get_error_message());
                    }
                    $result = $upgrader->install_package(array('source' => $working_dir, 'destination' => WP_PLUGIN_DIR, 'clear_destination' => false, 'abort_if_destination_exists' => false, 'clear_working' => true, 'hook_extra' => array('type' => 'plugin', 'action' => 'install')));
                    if (is_wp_error($result)) {
                        throw new Exception($result->get_error_message());
                    }
                    $activate = true;
                } catch (Exception $e) {
                    WC_Admin_Notices::add_custom_notice($plugin_to_install_id . '_install_error', sprintf(__('%1$s could not be installed (%2$s). <a href="%3$s">Please install it manually by clicking here.</a>', 'woocommerce'), $plugin_to_install['name'], $e->getMessage(), esc_url(admin_url('index.php?wc-install-plugin-redirect=' . $plugin_to_install['repo-slug']))));
                }
                // Discard feedback
                ob_end_clean();
            }
            wp_clean_plugins_cache();
            // Activate this thing
            if ($activate) {
                try {
                    $result = activate_plugin($plugin);
                    if (is_wp_error($result)) {
                        throw new Exception($result->get_error_message());
                    }
                } catch (Exception $e) {
                    WC_Admin_Notices::add_custom_notice($plugin_to_install_id . '_install_error', sprintf(__('%1$s was installed but could not be activated. <a href="%2$s">Please activate it manually by clicking here.</a>', 'woocommerce'), $plugin_to_install['name'], admin_url('plugins.php')));
                }
            }
        }
    }