Don't delay creation of system URLRequestContext until first use

components/proxy_config/pref_proxy_config_tracker_impl.cc

Index: components/proxy_config/pref_proxy_config_tracker_impl.cc
diff --git a/components/proxy_config/pref_proxy_config_tracker_impl.cc b/components/proxy_config/pref_proxy_config_tracker_impl.cc
index f8077aa9032038126769864d3a64ebc23e3f82f1..dce10933491fe9e3e7265c5021ca3ab9572bc10b 100644
--- a/components/proxy_config/pref_proxy_config_tracker_impl.cc
+++ b/components/proxy_config/pref_proxy_config_tracker_impl.cc
@@ -24,10 +24,12 @@
 //============================= ProxyConfigServiceImpl =======================
 
 ProxyConfigServiceImpl::ProxyConfigServiceImpl(
-    net::ProxyConfigService* base_service)
+    net::ProxyConfigService* base_service,
+    ProxyPrefs::ConfigState initial_config_state,
+    const net::ProxyConfig& initial_config)
     : base_service_(base_service),
-      pref_config_state_(ProxyPrefs::CONFIG_UNSET),
-      pref_config_read_pending_(true),
+      pref_config_state_(initial_config_state),
+      pref_config_(initial_config),
       registered_observer_(false) {
   // ProxyConfigServiceImpl is created on the UI thread, but used on the network
   // thread.
@@ -54,9 +56,6 @@ net::ProxyConfigService::ConfigAvailability
 ProxyConfigServiceImpl::GetLatestProxyConfig(net::ProxyConfig* config) {
   RegisterObserver();
 
-  if (pref_config_read_pending_)
-    return net::ProxyConfigService::CONFIG_PENDING;
-
   // Ask the base service if available.
   net::ProxyConfig system_config;
   ConfigAvailability system_availability =
@@ -79,7 +78,6 @@ void ProxyConfigServiceImpl::UpdateProxyConfig(
     ProxyPrefs::ConfigState config_state,
     const net::ProxyConfig& config) {
   DCHECK(thread_checker_.CalledOnValidThread());
-  pref_config_read_pending_ = false;
   pref_config_state_ = config_state;
   pref_config_ = config;
 
@@ -109,7 +107,7 @@ void ProxyConfigServiceImpl::OnProxyConfigChanged(
 
   // Check whether there is a proxy configuration defined by preferences. In
   // this case that proxy configuration takes precedence and the change event
-  // from the delegate proxy service can be disregarded.
+  // from the delegate proxy config service can be disregarded.
   if (!PrefProxyConfigTrackerImpl::PrefPrecedes(pref_config_state_)) {
     net::ProxyConfig actual_config;
     availability = GetLatestProxyConfig(&actual_config);
@@ -149,12 +147,11 @@ PrefProxyConfigTrackerImpl::~PrefProxyConfigTrackerImpl() {
 std::unique_ptr<net::ProxyConfigService>
 PrefProxyConfigTrackerImpl::CreateTrackingProxyConfigService(

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

The interface for CreateTrackingProxyConfigService() doesn't document whether
this can be called multiple times. Presumably it can't.

Care to add a DCHECK() that proxy_config_service_impl_ is null here, and add a
comment to the interface?

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

Done (Docs added to PrefProxyConfigTracker)

     std::unique_ptr<net::ProxyConfigService> base_service) {
-  proxy_config_service_impl_ =
-      new ProxyConfigServiceImpl(base_service.release());
+  proxy_config_service_impl_ = new ProxyConfigServiceImpl(
+      base_service.release(), config_state_, pref_config_);
   VLOG(1) << this << ": set chrome proxy config service to "
           << proxy_config_service_impl_;
-  if (proxy_config_service_impl_ && update_pending_)
-    OnProxyConfigChanged(config_state_, pref_config_);
+  update_pending_ = false;
 
   return std::unique_ptr<net::ProxyConfigService>(proxy_config_service_impl_);
 }