title: pwa angular 8 doesn't show "add to my home screen popup"
body: <p>my app is a an angular pwa, but it's not suggesting to install on google chrome, the button is also not showing up and also on f12, application, identification the button to add to home screen is not there.
  Anything wrong with my manifest?</p>
  
  <pre><code>{
    "name": "aaaa",
    "short_name": "aaa",
    "theme_color": "#1976d2",
    "background_color": "#fafafa",
    "display": "standalone",
    "scope": "./",
    "start_url": "/aaa/",
    "orientation": "landscape",
    "prefer_related_applications": true,
  
    "icons": [
  
      {
        "src": "assets/icons/android-icon-36x36.png",
        "sizes": "72x72",
        "type": "image/png"
      },
      {
        "src": "assets/icons/android-icon-48x48.png",
        "sizes": "72x72",
        "type": "image/png"
      },
  
      {
        "src": "assets/icons/android-icon-72x72.png",
        "sizes": "72x72",
        "type": "image/png"
      },
      {
        "src": "assets/icons/android-icon-96x96.png",
        "sizes": "96x96",
        "type": "image/png"
      },
      {
        "src": "assets/icons/android-icon-144x144.png",
        "sizes": "144x144",
        "type": "image/png"
      },
      {
        "src": "assets/icons/android-icon-192x192.png",
        "sizes": "192x192",
        "type": "image/png"
      },
      {
        "src": "assets/icons/apple-icon-57x57.png",
        "sizes": "57x57",
        "type": "image/png"
      },  
      {
        "src": "assets/icons/icons-512.png",
        "type": "image/png",
        "sizes": "512x512"
      }
  
    ]
  }
  </code></pre>
  
  <p>the images are indeed in those locations and I have zero errors when I run lighthouse audits</p>