chromium/chrome/test/data/extensions/api_test/management/launch_app_panel/manifest.json

{
  "name": "Launch App in Panel",
  "version": "1",
  "manifest_version": 2,
  "permissions": ["management"],
  "app": {
    "launch": {
      "local_path": "launch.html",
      "container": "panel"
    }
  }
}