make version of ts_mon compatible with appengine

infra_libs/test/httplib2_utils_test.py

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import os
 import unittest
 
-from infra_libs import http_metrics
+from infra_libs.ts_mon.common import http_metrics
 from infra_libs import httplib2_utils
 
 import httplib2
 import mock
 import oauth2client.client
 
 
 DATA_DIR = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'data')
 
 
@@ skipping 173 matching lines @@
 
     self.http._request.return_value = (
         httplib2.Response({'status': 200}),
         'content')
 
     _, _ = self.http.request('http://foo/')
     self.assertEqual(1, http_metrics.durations.get(
         {'name': 'test', 'client': 'httplib2'}).count)
     self.assertAlmostEqual(300, http_metrics.durations.get(
         {'name': 'test', 'client': 'httplib2'}).sum)