MD Settings: Update some Settings handlers to use new JS lifecycle management.

chrome/browser/ui/webui/settings/appearance_handler.h

 // Copyright (c) 2015 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_APPEARANCE_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_SETTINGS_APPEARANCE_HANDLER_H_
 
 #include "base/macros.h"
 #include "chrome/browser/ui/webui/settings/settings_page_ui_handler.h"
 #include "content/public/browser/notification_observer.h"
@@ skipping 13 matching lines @@
 
 // Chrome "Appearance" settings page UI handler.
 class AppearanceHandler : public SettingsPageUIHandler,
                           public content::NotificationObserver {
  public:
   explicit AppearanceHandler(content::WebUI* webui);
   ~AppearanceHandler() override;
 
   // SettingsPageUIHandler implementation.
   void RegisterMessages() override;
+  void OnJavascriptAllowed() override;
+  void OnJavascriptDisallowed() override;
 
  private:
   // content::NotificationObserver implementation.
   void Observe(int type,
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
   // Whether the theme can be reset.
   bool ResetThemeEnabled() const;
 
@@ skipping 12 matching lines @@
 
   // Used to register for relevant notifications.
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(AppearanceHandler);
 };
 
 }  // namespace settings
 
 #endif  // CHROME_BROWSER_UI_WEBUI_SETTINGS_APPEARANCE_HANDLER_H_