cros: Fix user image change crash

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

 // Copyright 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_CHROMEOS_CHANGE_PICTURE_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_SETTINGS_CHROMEOS_CHANGE_PICTURE_HANDLER_H_
 
 #include "base/macros.h"
 #include "base/scoped_observer.h"
 #include "chrome/browser/chromeos/camera_presence_notifier.h"
@@ skipping 108 matching lines @@
 
   // Index of the previous user image.
   int previous_image_index_;
 
   // Last user photo, if taken.
   gfx::ImageSkia user_photo_;
 
   // Data URL for |user_photo_|.
   std::string user_photo_data_url_;
 
+  ScopedObserver<user_manager::UserManager, ChangePictureHandler>
+      user_manager_observer_;
   ScopedObserver<CameraPresenceNotifier, ChangePictureHandler> camera_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ChangePictureHandler);
 };
 
 }  // namespace settings
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_SETTINGS_CHROMEOS_CHANGE_PICTURE_HANDLER_H_