- 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.cc
const net::ProxyConfig& config,
                  const base::Closure& callback) {
  auto proxy_service = getter->GetURLRequestContext()->proxy_service();
  proxy_service->ResetConfigService(base::WrapUnique(
      new net::ProxyConfigServiceFixed(config)));
  
  proxy_service->ForceReloadProxyConfig();
  RunCallbackInUI(callback);
}
void SetCertVerifyProcInIO(
    const scoped_refptr<net::URLRequestContextGetter>& context_getter,
    const AtomCertVerifier::VerifyProc& proc) {
  auto request_context = context_getter->GetURLRequestContext();
  static_cast<AtomCertVerifier*>(request_context->cert_verifier())->
      SetVerifyProc(proc);
}
void ClearHostResolverCacheInIO(