private void RegisterDownloadDelegate()
 {
     if (m_DownloadDelegateHandler != null)
     {
         return;
     }
     m_DownloadDelegateHandler = ScriptableObject.CreateInstance <DownloadDelegateHandler>();
     m_DownloadDelegateHandler.downloadManager = this;
     m_AssetStoreUtils.RegisterDownloadDelegate(m_DownloadDelegateHandler);
 }