components/mus/test_wm/manifest.json

{
  "manifest_version":  1,
  "name": "mojo:test_wm",
  "display_name": "Test Window Manager",
  "capabilities": {
    "required": {
      "mojo:mus": { "interfaces": [ "mus::mojom::WindowManagerWindowTreeFactory" ] }
    }
  }
}