title: registration.showNotification is not a function
body: <p>I'm using <a href="https://github.com/oliviertassinari/serviceworker-webpack-plugin" rel="noreferrer">serviceworker-webpack-plugin</a> to create a service worker in my reactjs apps. </p>
  
  <p>I've followed <a href="https://github.com/oliviertassinari/serviceworker-webpack-plugin/tree/master/docs" rel="noreferrer">the example</a> to register the service worker in the main thread. I've learnt that <code>Html5 Notification</code> doesn't work on Android chrome, so I used <code>registration.showNotification('Title', { body: 'Body.'});</code> instead of <code>new Notification('...')</code> to push notifications. But when I tested it on the desktop chrome, it throws this error </p>
  
  <pre><code>registration.showNotification is not a function
  </code></pre>
  
  <p>Is the registration.showNotification only available on Android chrome but not on the desktop? </p>
  
  <pre><code>public componentDidMount(){
  
      if ('serviceWorker' in navigator &amp;&amp;
          (window.location.protocol === 'https:' || window.location.hostname === 'localhost')
      ) {
          const registration = runtime.register();
  
          registerEvents(registration, {
              onInstalled: () =&gt; {
  
                  registration.showNotification('Title', { body: 'Body.'});
              }
          })
      } else {
          console.log('serviceWorker not available')
      }
  }
  </code></pre>