[SecureContext,
 NoInterfaceObject,
 Exposed=(Window,Worker)]
interface NavigatorStorage {
  readonly attribute StorageManager storage;
};
Navigator implements NavigatorStorage;
WorkerNavigator implements NavigatorStorage;

[SecureContext,
 Exposed=(Window,Worker)]
interface StorageManager {
  Promise<boolean> persisted();
  [Exposed=Window] Promise<boolean> persist();

  Promise<StorageEstimate> estimate();
};

dictionary StorageEstimate {
  unsigned long long usage;
  unsigned long long quota;
};