cros: Do not initialize gaia portal detector if not loading gaia

chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc

Index: chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
index 67f3955d0cff065655c886d05f624affa67a4076..c237e7d09c4de602945ff03121837b354e5a896e 100644
--- a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
@@ -241,6 +241,11 @@ GaiaScreenHandler::~GaiaScreenHandler() {
 }
 
 void GaiaScreenHandler::MaybePreloadAuthExtension() {
+  // We shall not have network portal detector initialized, which unnecessarily
+  // polls captive portal checking URL if we don't need to load gaia.

[jdufault, 2017/06/06 23:23:00]

Please add a link to go/bad-portal here.

// Don't create network portal detector if we don't need to load gaia. See
go/bad-portal for more context.

[Qiang(Joe) Xu, 2017/06/06 23:46:51]

Done.

+  if (!signin_screen_handler_->ShouldLoadGaia())
+    return;
+
   VLOG(1) << "MaybePreloadAuthExtension";
 
   if (!network_portal_detector_) {
@@ -254,8 +259,7 @@ void GaiaScreenHandler::MaybePreloadAuthExtension() {
 
   // If cookies clearing was initiated or |dns_clear_task_running_| then auth
   // extension showing has already been initiated and preloading is pointless.
-  if (signin_screen_handler_->ShouldLoadGaia() && !gaia_silent_load_ &&
-      !cookies_cleared_ && !dns_clear_task_running_ &&
+  if (!gaia_silent_load_ && !cookies_cleared_ && !dns_clear_task_running_ &&
       network_state_informer_->state() == NetworkStateInformer::ONLINE) {
     gaia_silent_load_ = true;
     gaia_silent_load_network_ = network_state_informer_->network_path();