text: importScripts('https://www.gstatic.com/firebasejs/3.9.0/firebase-app.js');
  importScripts('https://www.gstatic.com/firebasejs/3.9.0/firebase-messaging.js');
  importScripts('https://www.gstatic.com/firebasejs/3.5.2/firebase-database.js');
  
  firebase.initializeApp({
    'messagingSenderId': '378401206416'
  });
  
  const messaging = firebase.messaging();