Fix of "login is not defined" error in OOBE

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

 // Copyright (c) 2011 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 CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_OOBE_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_OOBE_UI_H_
 
 #include <map>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #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"
 
 namespace ash {
 class ScreenDimmer;
 }
 
 namespace base {
 class DictionaryValue;
 }  // namespace base
 
 namespace chromeos {
 class AppLaunchSplashScreenActor;
 class ArcKioskSplashScreenActor;
 class ArcTermsOfServiceScreenActor;
 class AutoEnrollmentCheckScreenActor;
-class BaseScreenHandler;
 class ControllerPairingScreenActor;
 class CoreOobeActor;
 class DeviceDisabledScreenActor;
 class EnableDebuggingScreenActor;
 class EnrollmentScreenActor;
 class EulaView;
 class ErrorScreen;
 class ErrorScreenHandler;
 class GaiaScreenHandler;
 class HIDDetectionView;
@@ skipping 113 matching lines @@
   }
 
   NetworkStateInformer* network_state_informer_for_test() const {
     return network_state_informer_.get();
   }
 
   // Does ReloadContent() if needed (for example, if material design mode has
   // 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:
   void OnCurrentScreenChanged(OobeScreen screen) override;
 
   // Type of UI.
   std::string display_type_;
 
   // Reference to NetworkStateInformer that handles changes in network
   // state.
@@ skipping 71 matching lines @@
   std::vector<base::Closure> ready_callbacks_;
 
   // List of registered observers.
   base::ObserverList<Observer> observer_list_;
 
   // Observer of CrosSettings watching the kRebootOnShutdown policy.
   std::unique_ptr<ShutdownPolicyHandler> shutdown_policy_handler_;
 
   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);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_OOBE_UI_H_