chromium/chrome/test/data/web_apps/theme_color.json

{
  "name": "theme_color web app",
  "icons": [
    {
      "src": "basic-192.png",
      "sizes": "192x192",
      "type": "image/png"
    }
  ],
  "start_url": "basic.html",
  "display": "standalone",
  "theme_color": "blue"
}