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      1 # Copyright 2013 The Chromium Authors. All rights reserved.
      2 # Use of this source code is governed by a BSD-style license that can be
      3 # found in the LICENSE file.
      4 
      5 from metrics import Metric
      6 from telemetry.value import scalar
      7 
      8 class LoadingMetric(Metric):
      9   """A metric for page loading time based entirely on window.performance"""
     10 
     11   def Start(self, page, tab):
     12     raise NotImplementedError()
     13 
     14   def Stop(self, page, tab):
     15     raise NotImplementedError()
     16 
     17   def AddResults(self, tab, results):
     18     load_timings = tab.EvaluateJavaScript('window.performance.timing')
     19 
     20     # NavigationStart relative markers in milliseconds.
     21     load_start = (
     22       float(load_timings['loadEventStart']) - load_timings['navigationStart'])
     23     results.AddValue(scalar.ScalarValue(
     24         results.current_page, 'load_start', 'ms', load_start))
     25 
     26     dom_content_loaded_start = (
     27       float(load_timings['domContentLoadedEventStart']) -
     28       load_timings['navigationStart'])
     29     results.AddValue(scalar.ScalarValue(
     30         results.current_page, 'dom_content_loaded_start', 'ms',
     31         dom_content_loaded_start))
     32 
     33     fetch_start = (
     34         float(load_timings['fetchStart']) - load_timings['navigationStart'])
     35     results.AddValue(scalar.ScalarValue(
     36         results.current_page, 'fetch_start', 'ms', fetch_start,
     37         important=False))
     38 
     39     request_start = (
     40         float(load_timings['requestStart']) - load_timings['navigationStart'])
     41     results.AddValue(scalar.ScalarValue(
     42         results.current_page, 'request_start', 'ms', request_start,
     43         important=False))
     44 
     45     # Phase measurements in milliseconds.
     46     domain_lookup_duration = (
     47         float(load_timings['domainLookupEnd']) -
     48         load_timings['domainLookupStart'])
     49     results.AddValue(scalar.ScalarValue(
     50         results.current_page, 'domain_lookup_duration', 'ms',
     51         domain_lookup_duration, important=False))
     52 
     53     connect_duration = (
     54         float(load_timings['connectEnd']) - load_timings['connectStart'])
     55     results.AddValue(scalar.ScalarValue(
     56         results.current_page, 'connect_duration', 'ms', connect_duration,
     57         important=False))
     58 
     59     request_duration = (
     60         float(load_timings['responseStart']) - load_timings['requestStart'])
     61     results.AddValue(scalar.ScalarValue(
     62         results.current_page, 'request_duration', 'ms', request_duration,
     63         important=False))
     64 
     65     response_duration = (
     66         float(load_timings['responseEnd']) - load_timings['responseStart'])
     67     results.AddValue(scalar.ScalarValue(
     68         results.current_page, 'response_duration', 'ms', response_duration,
     69         important=False))
     70