make version of ts_mon compatible with appengine

infra_libs/http_metrics.py

Index: infra_libs/http_metrics.py
diff --git a/infra_libs/http_metrics.py b/infra_libs/http_metrics.py
index 22e6eafbde7b736ca677932c9fac3160ec8ce8cd..22baa67564495b7399479cdeda623b2e7041c83d 100644
--- a/infra_libs/http_metrics.py
+++ b/infra_libs/http_metrics.py
@@ -2,12 +2,13 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-from infra_libs.ts_mon import metrics
+from infra_libs.ts_mon.metrics import CumulativeDistributionMetric
+from infra_libs.ts_mon.metrics import CounterMetric
 
-request_bytes = metrics.CumulativeDistributionMetric('http/request_bytes')
-response_bytes = metrics.CumulativeDistributionMetric('http/response_bytes')
-durations = metrics.CumulativeDistributionMetric('http/durations')
-response_status = metrics.CounterMetric('http/response_status')
+request_bytes = CumulativeDistributionMetric('http/request_bytes')
+response_bytes = CumulativeDistributionMetric('http/response_bytes')
+durations = CumulativeDistributionMetric('http/durations')
+response_status = CounterMetric('http/response_status')
 
 
 def _reset_for_testing():  # pragma: no cover