manifest.json

{
  "short_name": "Pesto",
  "name": "Pesto by Polymer",
  "display": "standalone",
  "icons": [{
    "src": "https://app-layout-assets.appspot.com/assets/pesto/icon-144.png",
    "sizes": "144x144",
    "type": "image/png"
  }, {
    "src": "https://app-layout-assets.appspot.com/assets/pesto/icon-256.png",
    "sizes": "256x256",
    "type": "image/png"
  }],
  "start_url": "index.html"
}