WebUI: Add JavaScript lifecycle-control to WebUIMessageHandler.

chrome/browser/ui/webui/settings/chromeos/easy_unlock_settings_handler.h

 // Copyright 2016 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_SETTINGS_CHROMEOS_EASY_UNLOCK_SETTINGS_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_SETTINGS_CHROMEOS_EASY_UNLOCK_SETTINGS_HANDLER_H_
 
 #include "base/macros.h"
 #include "chrome/browser/signin/easy_unlock_service_observer.h"
 #include "chrome/browser/ui/webui/settings/settings_page_ui_handler.h"
@@ skipping 13 matching lines @@
  public:
   // Returns nullptr if EasyUnlock is not allowed for this device.
   static EasyUnlockSettingsHandler* Create(
       content::WebUIDataSource* html_source,
       Profile* profile);
 
   ~EasyUnlockSettingsHandler() override;
 
   // SettingsPageUIHandler:
   void RegisterMessages() override;
-  void RenderViewReused() override;
+  void OnJavascriptAllowed() override;
+  void OnJavascriptDisallowed() override;
 
   // EasyUnlockServiceObserver:
   void OnTurnOffOperationStatusChanged() override;
 
  protected:
   explicit EasyUnlockSettingsHandler(Profile* profile);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(EasyUnlockSettingsHandlerTest, EnabledStatus);
   FRIEND_TEST_ALL_PREFIXES(EasyUnlockSettingsHandlerTest, TurnOffFlowStatus);
 
   void SendEnabledStatus();
   std::string GetTurnOffFlowStatus();
 
   // JS callbacks.
   void HandleGetEnabledStatus(const base::ListValue* args);
   void HandleStartTurnOnFlow(const base::ListValue* args);
   void HandleGetTurnOffFlowStatus(const base::ListValue* args);
   void HandleStartTurnOffFlow(const base::ListValue* args);
   void HandleCancelTurnOffFlow(const base::ListValue* args);
 
   Profile* const profile_;
 
   PrefChangeRegistrar profile_pref_registrar_;
 
-  bool observers_registered_;
-
   DISALLOW_COPY_AND_ASSIGN(EasyUnlockSettingsHandler);
 };
 
 }  // namespace settings
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_SETTINGS_CHROMEOS_EASY_UNLOCK_SETTINGS_HANDLER_H_