def list_metrics(self, project, page_size=0, page_token=None):
        """List metrics for the project associated with this client.

        :type project: str
        :param project: ID of the project whose metrics are to be listed.

        :type page_size: int
        :param page_size: maximum number of metrics to return, If not passed,
                          defaults to a value set by the API.

        :type page_token: str
        :param page_token: opaque marker for the next "page" of metrics. If not
                           passed, the API will return the first page of
                           metrics.

        :rtype: :class:`~google.api_core.page_iterator.Iterator`
        :returns: Iterator of
                  :class:`~google.cloud.logging.metric.Metric`
                  accessible to the current API.
        """
        path = "projects/%s" % (project,)
        page_iter = self._gapic_api.list_log_metrics(path, page_size=page_size)
        page_iter.client = self._client
        page_iter.next_page_token = page_token
        page_iter.item_to_value = _item_to_metric
        return page_iter