Move top_20 tests to a separate suite

tools/chrome_proxy/integration_tests/chrome_proxy_metrics_unittest.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 base64
 import unittest
 
-from integration_tests import chrome_proxy_metrics as metrics
-from integration_tests import network_metrics_unittest as network_unittest
+from common import chrome_proxy_metrics as metrics
+from common import network_metrics_unittest as network_unittest
 from telemetry.unittest_util import test_page_test_results
 
 TEST_EXTRA_VIA_HEADER = '1.1 EXTRA_VIA_HEADER'
 
 # Timeline events used in tests.
 # An HTML not via proxy.
 EVENT_HTML_DIRECT = network_unittest.NetworkMetricTest.MakeNetworkTimelineEvent(
     url='http://test.html1',
     response_headers={
         'Content-Type': 'text/html',
@@ skipping 413 matching lines @@
     self.assertTrue(exception_occurred)
 
     # Passing in zero responses should cause a failure.
     metric.SetEvents([])
     no_responses_exception = False
     try:
       metric.AddResultsForHTTPToDirectFallback(None, results, 'test.html2')
     except metrics.ChromeProxyMetricException:
       no_responses_exception = True
     self.assertTrue(no_responses_exception)