mash/webtest/manifest.json

{
  "manifest_version":  1,
  "name": "mojo:webtest",
  "display_name": "Web Test",
  "capabilities": {
    "provided": { "mash:launchable": [ "mash::mojom::Launchable" ] },
    "required": {
      "*": { "classes": [ "app" ] }
    }
  }
}