* 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
#include "net/cookies/cookie_monster.h"
#include "net/dns/mapped_host_resolver.h"
#include "net/http/http_auth_handler_factory.h"
#include "net/http/http_auth_preferences.h"
#include "net/http/http_auth_scheme.h"
#include "net/http/http_transaction_factory.h"
#include "net/log/net_log.h"
#include "net/traffic_annotation/network_traffic_annotation.h"
#include "net/url_request/data_protocol_handler.h"
#include "net/url_request/static_http_user_agent_settings.h"
#include "net/url_request/url_request_intercepting_job_factory.h"
#include "net/url_request/url_request_job_factory_impl.h"
#include "services/network/ignore_errors_cert_verifier.h"
#include "services/network/network_service.h"
#include "services/network/public/cpp/network_switches.h"
#include "services/network/url_request_context_builder_mojo.h"
#include "url/url_constants.h"
#if !BUILDFLAG(DISABLE_FTP_SUPPORT)
#include "net/url_request/ftp_protocol_handler.h"
#endif
using content::BrowserThread;
namespace atom {
namespace {
void SetupAtomURLRequestJobFactory(
    content::ProtocolHandlerMap* protocol_handlers,
    net::URLRequestContext* url_request_context,
    AtomURLRequestJobFactory* job_factory) {
  for (auto& protocol_handler : *protocol_handlers) {
    job_factory->SetProtocolHandler(protocol_handler.first,
                                    std::move(protocol_handler.second));