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

{
  "name": "<webview> guest focus test.",
  "manifest_version": 2,
  "version": "1",
  "permissions": [
    "webview"
  ],
  "app": {
     "background": {
       "scripts": ["test.js"]
     }
   },
   "webview": {
     "partitions": [
       {
         "name": "partition1",
         "accessible_resources": [
           "guest.js",
           "guest.html"
         ]
       }
    ]
  }
}