Update reference to page_test module to use legacy_page_test module

tools/chrome_proxy/integration_tests/chrome_proxy_metrics.py

 # Copyright 2014 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 json
 import logging
 import os
 import time
 
 from common import chrome_proxy_metrics
 from common import network_metrics
 from common.chrome_proxy_metrics import ChromeProxyMetricException
-from telemetry.page import page_test
+from telemetry.page import legacy_page_test
 from telemetry.value import scalar
 from telemetry.value import histogram_util
 from metrics import Metric
 
 class ChromeProxyMetric(network_metrics.NetworkMetric):
   """A Chrome proxy timeline metric."""
 
   def __init__(self):
     super(ChromeProxyMetric, self).__init__()
     self.compute_data_saving = True
@@ skipping 1061 matching lines @@
     except KeyError:
       raise ChromeProxyMetricException, 'No metrics found'
 
 # Returns whether |url| is a block-once test URL. Data Reduction Proxy has been
 # configured to always return block-once for these URLs.
 def IsTestUrlForBlockOnce(url):
   return (url == 'http://check.googlezip.net/blocksingle/' or
       url == ('http://chromeproxy-test.appspot.com/default?respBody=T0s='
               '&respHeader=eyJBY2Nlc3MtQ29udHJvbC1BbGxvdy1PcmlnaW4iOlsiKiJ'
               'dfQ==&respStatus=200&flywheelAction=block-once'))