chromium/chrome/test/data/extensions/platform_apps/web_view/focus_visibility/manifest.json

{
  "name": "App Test: Hidden <webview>  not Focusable",
  "manifest_version": 2,
  "description": "Loads a guest which monitors tabs",
  "version": "1",
  "permissions": [
      "webview"
  ],
  "app": {
    "background": {
      "scripts": ["background.js"]
    }
  }
}