Don't delay creation of system URLRequestContext until first use

components/proxy_config/pref_proxy_config_tracker_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_PROXY_CONFIG_PREF_PROXY_CONFIG_TRACKER_IMPL_H_
 #define COMPONENTS_PROXY_CONFIG_PREF_PROXY_CONFIG_TRACKER_IMPL_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 19 matching lines @@
 
 // A net::ProxyConfigService implementation that applies preference proxy
 // settings (pushed from PrefProxyConfigTrackerImpl) as overrides to the proxy
 // configuration determined by a baseline delegate ProxyConfigService on
 // non-ChromeOS platforms. ChromeOS has its own implementation of overrides in
 // chromeos::ProxyConfigServiceImpl.
 class ProxyConfigServiceImpl : public net::ProxyConfigService,
                                public net::ProxyConfigService::Observer {
  public:
   // Takes ownership of the passed |base_service|.
-  // GetLatestProxyConfig returns ConfigAvailability::CONFIG_PENDING until
-  // UpdateProxyConfig has been called.
-  explicit ProxyConfigServiceImpl(net::ProxyConfigService* base_service);
+  ProxyConfigServiceImpl(net::ProxyConfigService* base_service,

[eroman, 2017/05/12 21:12:59]

If you are changing the signature anyway, want to make this a unique_ptr?

[mmenke, 2017/05/12 21:29:57]

SGTM, done

+                         ProxyPrefs::ConfigState initial_config_state,
+                         const net::ProxyConfig& initial_config);
   ~ProxyConfigServiceImpl() override;
 
   // ProxyConfigService implementation:
   void AddObserver(net::ProxyConfigService::Observer* observer) override;
   void RemoveObserver(net::ProxyConfigService::Observer* observer) override;
   ConfigAvailability GetLatestProxyConfig(net::ProxyConfig* config) override;
   void OnLazyPoll() override;
 
   // Method on IO thread that receives the preference proxy settings pushed from
   // PrefProxyConfigTrackerImpl.
@@ skipping 11 matching lines @@
   std::unique_ptr<net::ProxyConfigService> base_service_;
   base::ObserverList<net::ProxyConfigService::Observer, true> observers_;
 
   // Tracks configuration state of |pref_config_|. |pref_config_| is valid only
   // if |pref_config_state_| is not CONFIG_UNSET.
   ProxyPrefs::ConfigState pref_config_state_;
 
   // Configuration as defined by prefs.
   net::ProxyConfig pref_config_;
 
-  // Flag that indicates that a PrefProxyConfigTracker needs to inform us
-  // about a proxy configuration before we may return any configuration.
-  bool pref_config_read_pending_;
-
   // Indicates whether the base service registration is done.
   bool registered_observer_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyConfigServiceImpl);
 };
 
 // A class that tracks proxy preferences. It translates the configuration
 // to net::ProxyConfig and pushes the result over to the IO thread for
@@ skipping 82 matching lines @@
   PrefChangeRegistrar proxy_prefs_;
 
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefProxyConfigTrackerImpl);
 };
 
 #endif  // COMPONENTS_PROXY_CONFIG_PREF_PROXY_CONFIG_TRACKER_IMPL_H_