* 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
}
  protocol_handlers->clear();
  job_factory->SetProtocolHandler(url::kAboutScheme,
                                  std::make_unique<AboutProtocolHandler>());
  job_factory->SetProtocolHandler(url::kDataScheme,
                                  std::make_unique<net::DataProtocolHandler>());
  job_factory->SetProtocolHandler(
      url::kFileScheme,
      std::make_unique<asar::AsarProtocolHandler>(
          base::CreateTaskRunnerWithTraits(
              {base::MayBlock(), base::TaskPriority::USER_BLOCKING,
               base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN})));
  job_factory->SetProtocolHandler(
      url::kHttpScheme,
      std::make_unique<HttpProtocolHandler>(url::kHttpScheme));
  job_factory->SetProtocolHandler(
      url::kHttpsScheme,
      std::make_unique<HttpProtocolHandler>(url::kHttpsScheme));
  job_factory->SetProtocolHandler(
      url::kWsScheme, std::make_unique<HttpProtocolHandler>(url::kWsScheme));
  job_factory->SetProtocolHandler(
      url::kWssScheme, std::make_unique<HttpProtocolHandler>(url::kWssScheme));
#if !BUILDFLAG(DISABLE_FTP_SUPPORT)
  auto* host_resolver = url_request_context->host_resolver();
  job_factory->SetProtocolHandler(
      url::kFtpScheme, net::FtpProtocolHandler::Create(host_resolver));
#endif
}
}  
class ResourceContext : public content::ResourceContext {