Fix of "login is not defined" error in OOBE

chrome/browser/ui/webui/chromeos/login/oobe_ui.h

Index: chrome/browser/ui/webui/chromeos/login/oobe_ui.h
diff --git a/chrome/browser/ui/webui/chromeos/login/oobe_ui.h b/chrome/browser/ui/webui/chromeos/login/oobe_ui.h
index 80e080728fd97959a31b3233af3867d83fb7c671..1ee84627722512816778d71306c340b966ea1c7d 100644
--- a/chrome/browser/ui/webui/chromeos/login/oobe_ui.h
+++ b/chrome/browser/ui/webui/chromeos/login/oobe_ui.h
@@ -16,6 +16,7 @@
 #include "base/observer_list.h"
 #include "chrome/browser/chromeos/login/oobe_screen.h"
 #include "chrome/browser/chromeos/settings/shutdown_policy_handler.h"
+#include "chrome/browser/ui/webui/chromeos/login/base_screen_handler.h"
 #include "chrome/browser/ui/webui/chromeos/login/core_oobe_handler.h"
 #include "content/public/browser/web_ui_controller.h"
 
@@ -32,7 +33,6 @@ class AppLaunchSplashScreenActor;
 class ArcKioskSplashScreenActor;
 class ArcTermsOfServiceScreenActor;
 class AutoEnrollmentCheckScreenActor;
-class BaseScreenHandler;
 class ControllerPairingScreenActor;
 class CoreOobeActor;
 class DeviceDisabledScreenActor;
@@ -166,7 +166,44 @@ class OobeUI : public content::WebUIController,
   // changed).
   void UpdateLocalizedStringsIfNeeded();
 
+  // Executes javascript calls that were deferred while the instance was not
+  // initialized yet.
+  void ExecuteDeferredJSCalls();
+
+  // Calls javascript method if the instance is already initialized, or defers
+  // the call until it gets initialized.
+  template <typename... Args>
+  void CallJSOrDefer(const std::string& function_name,
+                     BaseScreenHandler* screen_handler,
+                     const Args&... args) {
+    if (is_initialized_) {
+      screen_handler->CallJS(function_name, args...);
+    } else {
+      // Note that std::conditional is used here in order to obtain a sequence
+      // of base::Value types with the length equal to sizeof...(Args); the C++
+      // template parameter pack expansion rules require that the name of the
+      // parameter pack appears in the pattern, even though the elements of the
+      // Args pack are not actually in this code.
+      deferred_js_calls_.push_back(base::Bind(
+          &OobeUI::ExecuteDeferredJSCall<
+              typename std::conditional<true, base::Value, Args>::type...>,
+          base::Unretained(this), function_name, screen_handler,
+          base::Passed(::login::MakeValue(args).CreateDeepCopy())...));
+    }
+  }
+
  private:
+  // Calls javascript method.
+  //
+  // Note that the Args template parameter pack should consist of types
+  // convertible to base::Value.
+  template <typename... Args>
+  void ExecuteDeferredJSCall(const std::string& function_name,
+                             BaseScreenHandler* screen_handler,
+                             std::unique_ptr<Args>... args) {
+    screen_handler->CallJS(function_name, *args...);
+  }
+
   void AddScreenHandler(std::unique_ptr<BaseScreenHandler> handler);
 
   // CoreOobeHandler::Delegate implementation:
@@ -258,6 +295,16 @@ class OobeUI : public content::WebUIController,
 
   std::unique_ptr<ash::ScreenDimmer> screen_dimmer_;
 
+  // Whether the instance is initialized.
+  //
+  // The instance becomes initialized after the corresponding message is
+  // received from javascript side.
+  bool is_initialized_ = false;
+
+  // Javascript calls that have been deferred while the instance was not
+  // initialized yet.
+  std::vector<base::Closure> deferred_js_calls_;
+
   DISALLOW_COPY_AND_ASSIGN(OobeUI);
 };