* Output of `node_modules/.bin/electron --version`: 4.0.0-beta.5
* Operating System (Platform and Version): macOS 10.14
* Output of `node_modules/.bin/electron --version` on last known working Electron version (if applicable): There is no issue with Electron v3.

**Expected Behavior**
Cookies should be persisted in a webview that uses partition.

**Actual behavior**
Cookies are lost after relaunching app.

**To Reproduce**
1. Create webview with partition: `<webview partition="persist:webview"/>`
2. Sign in to GitHub to create a cookie.
3. Relaunch app.
4. When webview opens again, the cookies are lost. 
atom/browser/net/url_request_context_getter.cc
SystemNetworkContextManager::CreateDefaultNetworkContextParams();
  network_context_params->user_agent = browser_context_->GetUserAgent();
  network_context_params->http_cache_enabled =
      browser_context_->CanUseHttpCache();
  network_context_params->accept_language =
      net::HttpUtil::GenerateAcceptLanguageHeader(
          AtomBrowserClient::Get()->GetApplicationLocale());
  network_context_params->enable_data_url_support = false;
  if (!browser_context_->IsOffTheRecord()) {
    auto base_path = browser_context_->GetPath();
    network_context_params->http_cache_path =
        base_path.Append(chrome::kCacheDirname);
    network_context_params->http_cache_max_size =
        browser_context_->GetMaxCacheSize();
    network_context_params->http_server_properties_path =
        base_path.Append(chrome::kNetworkPersistentStateFilename);
    network_context_params->cookie_path =
        base_path.Append(chrome::kCookieFilename);
    network_context_params->channel_id_path =
        base_path.Append(chrome::kChannelIDFilename);
    network_context_params->restore_old_session_cookies = false;
    network_context_params->persist_session_cookies = false;
  }
  
  
  
  
  return network_context_params;
}
void URLRequestContextGetter::Handle::LazyInitialize() {