chromium/extensions/test/data/web_view/dialog/manifest.json

{
  "name": "Packaged App Test: <webview> JavaScript Dialogs",
  "description": "Verifies that the <webview> Dialog API works as expected.",
  "version": "2",
  "manifest_version": 2,
  "permissions": [
    "webview"
  ],
  "app": {
    "background": {
      "scripts": ["test.js"]
    }
  }
}