chromium/chrome/test/data/banners/manifest_with_narrow_screenshots.json

{
  "name": "PWA with only narrow screenshots",
  "description": "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua",
  "screenshots": [
    {
      "src": "screenshot1-portrait.jpeg",
      "type": "image/jpeg",
      "sizes": "409x728",
      "form_factor": "narrow"
    },
    {
      "src": "screenshot1-portrait-samesize.jpeg",
      "type": "image/jpeg",
      "sizes": "409x728"
    }
  ],
  "icons": [
    {
      "src": "image-512px.png",
      "sizes": "512x512",
      "type": "image/png"
    }
  ],
  "scope": ".",
  "start_url": "manifest_test_page.html",
  "display": "standalone"
}