Fix a used-after-free caused by an unremoved Observer.

chrome/browser/ui/webui/settings/profile_info_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_PROFILE_INFO_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_SETTINGS_PROFILE_INFO_HANDLER_H_
 
 #include <memory>
 
 #include "base/macros.h"
+#include "base/scoped_observer.h"
 #include "build/build_config.h"
 #include "chrome/browser/profiles/profile_attributes_storage.h"
 #include "chrome/browser/ui/webui/settings/settings_page_ui_handler.h"
 
 #if defined(OS_CHROMEOS)
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #endif
 
 class Profile;
 
 namespace settings {
 
 class ProfileInfoHandler : public SettingsPageUIHandler,
 #if defined(OS_CHROMEOS)
                            public content::NotificationObserver,
 #endif
                            public ProfileAttributesStorage::Observer {
  public:
   static const char kProfileInfoChangedEventName[];
 
   explicit ProfileInfoHandler(Profile* profile);
-  ~ProfileInfoHandler() override {}
+  ~ProfileInfoHandler() override;
 
   // SettingsPageUIHandler implementation.
   void RegisterMessages() override;
   void OnJavascriptAllowed() override;
   void OnJavascriptDisallowed() override;
 
 #if defined(OS_CHROMEOS)
   // content::NotificationObserver implementation.
   void Observe(int type,
                const content::NotificationSource& source,
@@ skipping 12 matching lines @@
   // Callbacks from the page.
   void HandleGetProfileInfo(const base::ListValue* args);
 
   void PushProfileInfo();
 
   std::unique_ptr<base::DictionaryValue> GetAccountNameAndIcon() const;
 
   // Weak pointer.
   Profile* profile_;
 
+  ScopedObserver<ProfileAttributesStorage, ProfileInfoHandler>
+      profile_observer_;
+
 #if defined(OS_CHROMEOS)
   // Used to listen to ChromeOS user image changes.
   content::NotificationRegistrar registrar_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(ProfileInfoHandler);
 };
 
 }  // namespace settings
 
 #endif  // CHROME_BROWSER_UI_WEBUI_SETTINGS_PROFILE_INFO_HANDLER_H_