title: Why is my 'add to home screen' Web App Install Banner not showing up in my web app
body: <p>I've created a service-worker and <code>manifest.json</code> file in order to display an 'add to home screen' Web App Install Banner for Chrome Browser Users.</p>
  
  <p>It is not working as intended.</p>
  
  <p>Here is my <code>manifest.json</code> file</p>
  
  <pre><code>{
    "name": "MySite",
    "short_name": "Mysite",
    "start_url": "./?utm_source=homescreen",
    "icons": [{
        "src": "assets/cacheable/images/shortcut/120x120.png",
        "sizes": "128x128",
        "type": "image/png"
      }, {
        "src": "assets/cacheable/images/shortcut/142x142.png",
        "sizes": "142x142",
        "type": "image/png"
      }, {
        "src": "assets/cacheable/images/shortcut/192x192.png",
        "sizes": "192x192",
        "type": "image/png"
      }, {
        "src": "assets/cacheable/images/shortcut/192x192.png",
        "sizes": "384x384",
        "type": "image/png"
      }],
    "orientation": "portrait" ,
    "background_color": "#fff",
    "display": "standalone",
    "theme_color": "#fff"
  }
  </code></pre>
  
  <p>Please let me know if I forgot to add anything?</p>