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

{
  "name": "WebP test app",
  "icons": [
    {
      "src": "webp-icon.webp",
      "sizes": "192x192",
      "type": "image/webp"
    }
  ],
  "start_url": "manifest_test_page.html",
  "display": "standalone",
  "orientation": "landscape"
}