static void content_changed_callback(IntPtr target, IntPtr calldata, IntPtr closure)
{
ContentControl cc = (ContentControl)NativeDependencyObjectHelper.FromIntPtr(closure);
var oldContent = Value.ToObject(typeof(object), NativeMethods.content_control_changed_event_args_get_old_content(calldata));
var newContent = Value.ToObject(typeof(object), NativeMethods.content_control_changed_event_args_get_new_content(calldata));
cc.OnContentChanged(oldContent, newContent);
cc.RaiseUIAContentChanged(oldContent, newContent);
}