[Telemetry] Move gpu_timeline metrics to telemetry.web_perf

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 metrics import test_page_test_results
+from telemetry.unittest_util import test_page_test_results
 
 
 # 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',
         'Content-Length': str(len(network_unittest.HTML_BODY)),
         },
@@ skipping 314 matching lines @@
     metric.SetEvents([EVENT_HTML_DIRECT,
                        EVENT_HTML_DIRECT,
                        EVENT_IMAGE_DIRECT])
     exception_occurred = False
     try:
       metric.AddResultsForHTTPToDirectFallback(None, results, 'test.html2')
     except metrics.ChromeProxyMetricException:
       exception_occurred = True
     # The first response was expected through the HTTP fallback proxy.
     self.assertTrue(exception_occurred)