Future<FileSystem> requestFileSystem(int size, { bool persistent: false })

Access a sandboxed file system of the specified size. If persistent is true, the application will request permission from the user to create lasting storage. This storage cannot be freed without the user's permission. Returns a Future whose value stores a reference to the sandboxed file system for use. Because the file system is sandboxed, applications cannot access file systems created in other web pages.

Source

Future<FileSystem> requestFileSystem(int size, {bool persistent: false}) {
  return _requestFileSystem(persistent ? 1 : 0, size);
}