resume method
Resume the task
If no resume data is available for this task, the call to resume will return false and the task is not resumed. If resume data is available, the call to resume will return true, but this does not guarantee that resuming is actually possible, just that the task is now enqueued for resume. If the task is able to resume, it will, otherwise it will restart the task from scratch, or fail.
Implementation
Future<bool> resume(DownloadTask task) => _downloader.resume(task);