- Electron version: 1.4.3
- Operating system:  @win7
- description:

working on a download app with electron and angular. 
By using webContents.downloadUrl, webContents.session.on('will-download', handler) I can make download function work well, however, I could not find a api to save download progress before closing electron app so that I can restore download when this app is started next time.

Excepted Result:
1. user click 'download' button to download a 1G file.
2. after 500M is downloaded, user quit the app
3. one hour later, user open this app again, and downloading can automatically be restored

atom/browser/api/atom_api_download_item.h
bool IsPaused() const;
  void Resume();
  bool CanResume() const;
  void Cancel();
  int64_t GetReceivedBytes() const;
  int64_t GetTotalBytes() const;
  std::string GetMimeType() const;
  bool HasUserGesture() const;
  std::string GetFilename() const;
  std::string GetContentDisposition() const;
  const GURL& GetURL() const;
  content::DownloadItem::DownloadState GetState() const;
  bool IsDone() const;
  void SetSavePath(const base::FilePath& path);
  base::FilePath GetSavePath() const;
 protected:
  DownloadItem(v8::Isolate* isolate, content::DownloadItem* download_item);
  ~DownloadItem();
  
  void OnDownloadUpdated(content::DownloadItem* download) override;
  void OnDownloadDestroyed(content::DownloadItem* download) override;
 private:
  base::FilePath save_path_;
  content::DownloadItem* download_item_;
  DISALLOW_COPY_AND_ASSIGN(DownloadItem);
};
}  
}  
#endif