- 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_session.h
mate::Arguments* args);
  void ClearHostResolverCache(mate::Arguments* args);
  void AllowNTLMCredentialsForDomains(const std::string& domains);
  void SetUserAgent(const std::string& user_agent, mate::Arguments* args);
  std::string GetUserAgent();
  void GetBlobData(const std::string& uuid,
                   const AtomBlobReader::CompletionCallback& callback);
  v8::Local<v8::Value> Cookies(v8::Isolate* isolate);
  v8::Local<v8::Value> Protocol(v8::Isolate* isolate);
  v8::Local<v8::Value> WebRequest(v8::Isolate* isolate);
 protected:
  Session(v8::Isolate* isolate, AtomBrowserContext* browser_context);
  ~Session();
  
  void OnDownloadCreated(content::DownloadManager* manager,
                         content::DownloadItem* item) override;
 private:
  
  v8::Global<v8::Value> cookies_;
  v8::Global<v8::Value> protocol_;
  v8::Global<v8::Value> web_request_;
  
  std::string devtools_network_emulation_client_id_;
  scoped_refptr<AtomBrowserContext> browser_context_;
  DISALLOW_COPY_AND_ASSIGN(Session);
};
}  
}  
#endif