- Electron version: 1.1.0
- Operating system: Windows
- Use case: cleanup and reporting tasks executed on quit (headless), which may take time and should not prevent from opening a new instance.
- Proposed solutions:
  - new _app.releaseSingleInstance()_ API which free the singleInstance lock
  - replace _app.releaseSingleInstance()_ API by an event listener (which may be listened/unlistened)
  - [app.makeSingleInstance](https://github.com/electron/electron/blob/master/docs/api/app.md#appmakesingleinstancecallback) returns the result of the callback function. So we can choose to quit or not in a more accurate way.
  - Provide a communication channel between the new instance and the main one (in callback arguments)

atom/browser/api/atom_api_app.h
void SelectClientCertificate(
      content::WebContents* web_contents,
      net::SSLCertRequestInfo* cert_request_info,
      std::unique_ptr<content::ClientCertificateDelegate> delegate) override;
  
  void OnGpuProcessCrashed(base::TerminationStatus exit_code) override;
 private:
  
  base::FilePath GetPath(mate::Arguments* args, const std::string& name);
  void SetPath(mate::Arguments* args,
               const std::string& name,
               const base::FilePath& path);
  void SetDesktopName(const std::string& desktop_name);
  bool MakeSingleInstance(
      const ProcessSingleton::NotificationCallback& callback);
  std::string GetLocale();
#if defined(USE_NSS_CERTS)
  void ImportCertificate(const base::DictionaryValue& options,
                         const net::CompletionCallback& callback);
#endif
  std::unique_ptr<ProcessSingleton> process_singleton_;
#if defined(USE_NSS_CERTS)
  std::unique_ptr<CertificateManagerModel> certificate_manager_model_;
#endif
  DISALLOW_COPY_AND_ASSIGN(App);
};
}  
}  
#endif