unique_lock<mutex> lock(cef_mutex);
if (--cef_thread_refcount == 0) {
CefPostTask(TID_UI, new CEFTaskAdapter(&CefQuitMessageLoop));
unique_lock<mutex> lock(cef_mutex);
if (--cef_thread_refcount == 0) {
CefPostTask(TID_UI, new CEFTaskAdapter(&CefQuitMessageLoop));