chromium/chrome/test/data/extensions/api_test/keybinding/action/manifest.json

{
  "name": "Action via keyboard shortcuts",
  "version": "1.0",
  "manifest_version": 3,
  "background": {
    "service_worker": "worker.js"
  },
  "action": {},
  "commands": {
    "_execute_action": {
      "suggested_key": "Ctrl+Shift+U"
    }
  }
}