[Telemetry] Add a page set option to use all cold page loads.

tools/perf/perf_tools/page_cycler.py

 # Copyright (c) 2012 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.
 
 """The page cycler measurement.
 
 This measurement registers a window load handler in which is forces a layout and
 then records the value of performance.now(). This call to now() measures the
 time from navigationStart (immediately after the previous page's beforeunload
 event) until after the layout in the page's load event. In addition, two garbage
@@ skipping 18 matching lines @@
 
 class PageCycler(page_measurement.PageMeasurement):
   def AddCommandLineOptions(self, parser):
     # The page cyclers should default to 10 iterations. In order to change the
     # default of an option, we must remove and re-add it.
     pageset_repeat_option = parser.get_option('--pageset-repeat')
     pageset_repeat_option.default = 10
     parser.remove_option('--pageset-repeat')
     parser.add_option(pageset_repeat_option)
 
+    parser.add_option('--cold-page-loads', action='store_true',

[nduca, 2013/06/20 19:54:15]

rather you not expose it as a commandline. just block your bot hookup of this on
dtus benchmark objects.

[tonyg, 2013/06/21 22:36:18]

Done (reluctantly, as I still think this is a useful option).

+        help='Make page loads cold by clearing browser cache between loads.')
+
+
   def WillRunPageSet(self, tab, results):
     # Avoid paying for a cross-renderer navigation on the first page on legacy
     # page cyclers which use the filesystem.
     if tab.browser.http_server:
       tab.Navigate(tab.browser.http_server.UrlOf('nonexistent.html'))
 
     with open(os.path.join(os.path.dirname(__file__),
                            'page_cycler.js'), 'r') as f:
       self.page_cycler_js = f.read()  # pylint: disable=W0201
 
@@ skipping 101 matching lines @@
     for h in self.histograms:
       h.GetValue(page, tab, results)
 
     results.Add('page_load_time', 'ms',
                 int(float(tab.EvaluateJavaScript('__pc_load_time'))),
                 chart_name='times')
 
   def DidRunPageSet(self, tab, results):
     self.MeasureMemory(tab, results)
     self.MeasureIO(tab, results)