cros: Fix user image change crash

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

Index: chrome/browser/ui/webui/settings/chromeos/change_picture_handler.h
diff --git a/chrome/browser/ui/webui/settings/chromeos/change_picture_handler.h b/chrome/browser/ui/webui/settings/chromeos/change_picture_handler.h
index 55e718bfbf1cb78ad84e835c5ca1a56dcf74435d..a213282241e70498ac8684f802cc4d9ef1446939 100644
--- a/chrome/browser/ui/webui/settings/chromeos/change_picture_handler.h
+++ b/chrome/browser/ui/webui/settings/chromeos/change_picture_handler.h
@@ -126,6 +126,8 @@ class ChangePictureHandler : public ::settings::SettingsPageUIHandler,
   // 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);