Fix resource leak on extension window closing.

chrome/browser/chromeos/arc/arc_auth_service.cc

Index: chrome/browser/chromeos/arc/arc_auth_service.cc
diff --git a/chrome/browser/chromeos/arc/arc_auth_service.cc b/chrome/browser/chromeos/arc/arc_auth_service.cc
index 87d9ede5ba06b5b253fd416dd8a10d14b4ff200a..6ecf1f66b251e7b259f6138e40ed6b197d9550e5 100644
--- a/chrome/browser/chromeos/arc/arc_auth_service.cc
+++ b/chrome/browser/chromeos/arc/arc_auth_service.cc
@@ -639,8 +639,9 @@ void ArcAuthService::RemoveObserver(Observer* observer) {
 }
 
 void ArcAuthService::CloseUI() {
+  ui_page_ = UIPage::NO_PAGE;
+  ui_page_status_.clear();
   FOR_EACH_OBSERVER(Observer, observer_list_, OnOptInUIClose());
-  SetUIPage(UIPage::NO_PAGE, base::string16());
   if (!g_disable_ui_for_testing)
     ArcAuthNotification::Hide();
 }