Add upstream

wp-content/plugins/jetpack/modules/pwa.php

@@ -0,0 +1,42 @@
+<?php
+/**
+ * Module Name: Progressive Web Apps
+ * Module Description: Speed up and improve the reliability of your site using the latest in web technology.
+ * Sort Order: 38
+ * Recommendation Order: 18
+ * First Introduced: 5.6.0
+ * Requires Connection: Yes
+ * Auto Activate: No
+ * Module Tags: Developers
+ * Feature: Traffic
+ * Additional Search Queries: manifest, pwa, progressive
+ */
+
+require_once ( JETPACK__PLUGIN_DIR . 'modules/pwa/class.jetpack-pwa-helpers.php' );
+require_once ( JETPACK__PLUGIN_DIR . 'modules/pwa/class.jetpack-pwa-manifest.php' );
+
+class Jetpack_PWA {
+	/**
+	 * @var Jetpack_PWA
+	 */
+	private static $__instance = null;
+
+	/**
+	 * Singleton implementation
+	 *
+	 * @return Jetpack_PWA
+	 */
+	public static function instance() {
+		if ( is_null( self::$__instance ) ) {
+			self::$__instance = new Jetpack_PWA;
+		}
+
+		return self::$__instance;
+	}
+
+	private function __construct() {
+		Jetpack_PWA_Manifest::instance();
+	}
+}
+
+Jetpack_PWA::instance();