Collect tab timing information for use in telementry-based startup tests

tools/perf/perf_tools/startup_measurement.py

 # Copyright (c) 2013 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
 
 from telemetry.page import page_measurement
 
 # Test how long Chrome takes to load when warm.
 class PerfWarm(page_measurement.PageMeasurement):
   HISTOGRAMS_TO_RECORD = {
     'messageloop_start_time' :
         'Startup.BrowserMessageLoopStartTimeFromMainEntry',
     'window_display_time' : 'Startup.BrowserWindowDisplay',
     'open_tabs_time' : 'Startup.BrowserOpenTabs'}
 
   def __init__(self):
     super(PerfWarm, self).__init__(needs_browser_restart_after_each_run=True,
                                    discard_first_result=True)
 
   def CustomizeBrowserOptions(self, options):
+    options.AppendExtraBrowserArg('--enable-stats-collection-bindings')
+    options.AppendExtraBrowserArg(
+          '--reduce-security-for-stats-collection-tests')
+
+    # Old commandline flags used for reference builds.
     options.AppendExtraBrowserArg('--dom-automation')
-    options.AppendExtraBrowserArg('--reduce-security-for-dom-automation-tests')
+    options.AppendExtraBrowserArg(
+          '--reduce-security-for-dom-automation-tests')
 
   def MeasurePage(self, page, tab, results):
-    get_histogram_js = "domAutomationController.getBrowserHistogram(\"%s\")"
+    # TODO(jeremy): Remove references to
+    # domAutomationController.getBrowserHistogram when we update the reference
+    # builds.
+    get_histogram_js = ('(window.statsCollectionController ?'
+        'statsCollectionController :'
+        'domAutomationController).getBrowserHistogram("%s")')
+
 
     for display_name, histogram_name in self.HISTOGRAMS_TO_RECORD.iteritems():
       result = tab.EvaluateJavaScript(get_histogram_js % histogram_name)
       result = json.loads(result)
       measured_time = 0
 
       if 'sum' in result:
         # For all the histograms logged here, there's a single entry so sum
         # is the exact value for that entry.
         measured_time = result['sum']
       elif 'buckets' in result:
         measured_time = \
             (result['buckets'][0]['high'] + result['buckets'][0]['low']) / 2
 
       results.Add(display_name, 'ms', measured_time)