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

{
  "name": "<webview> test that allows WebView to be created after app has started.",
  "manifest_version": 2,
  "version": "1",
  "permissions": [
    "webview"
  ],
  "app": {
    "background": {
      "scripts": ["test.js"]
    }
  }
}