def _build_has_dcheck_always_on(self):
        args_gn_file = self._build_path('args.gn')
        if not self._filesystem.exists(args_gn_file):
            _log.error('Unable to find %s', args_gn_file)
            return False
        contents = self._filesystem.read_text_file(args_gn_file)
        return bool(
            re.search(r'^\s*dcheck_always_on\s*=\s*true\s*(#.*)?$', contents,
                      re.MULTILINE))