Telemetry: re-enable cpu metric for page_cycler.

tools/perf/measurements/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 63 matching lines @@
     # Avoid paying for a cross-renderer navigation on the first page on legacy
     # page cyclers which use the filesystem.
     tab.Navigate(tab.browser.http_server.UrlOf('nonexistent.html'))
 
   def WillNavigateToPage(self, page, tab):
     page.script_to_evaluate_on_commit = self._page_cycler_js
     if self.ShouldRunCold(page.url):
       tab.ClearCache(force=True)
     if self._report_speed_index:
       self._speedindex_metric.Start(page, tab)
+    self._cpu_metric.Start(page, tab)
 
   def DidNavigateToPage(self, page, tab):
     self._memory_metric.Start(page, tab)
     self._power_metric.Start(page, tab)
-    # TODO(qyearsley): Uncomment the following line and move it to
-    # WillNavigateToPage once the cpu metric has been changed.
-    # This is being temporarily commented out to let the page cycler
-    # results return to how they were before the cpu metric was added.
-    # self._cpu_metric.Start(page, tab) See crbug.com/301714.
     if self._record_v8_object_stats:
       self._v8_object_stats_metric.Start(page, tab)
 
   def CustomizeBrowserOptions(self, options):
     memory.MemoryMetric.CustomizeBrowserOptions(options)
     power.PowerMetric.CustomizeBrowserOptions(options)
     iometric.IOMetric.CustomizeBrowserOptions(options)
     options.AppendExtraBrowserArgs('--js-flags=--expose_gc')
 
     if self._record_v8_object_stats:
@@ skipping 32 matching lines @@
                 int(float(tab.EvaluateJavaScript('__pc_load_time'))),
                 chart_name=chart_name_prefix+'times')
 
     self._has_loaded_page[page.url] += 1
 
     self._power_metric.Stop(page, tab)
     self._memory_metric.Stop(page, tab)
     self._memory_metric.AddResults(tab, results)
     self._power_metric.AddResults(tab, results)
 
-    # TODO(qyearsley): Uncomment the following line when CPU metric is
-    # changed. See crbug.com/301714.
-    # self._cpu_metric.Stop(page, tab)
-    # self._cpu_metric.AddResults(tab, results)
+    self._cpu_metric.Stop(page, tab)
+    self._cpu_metric.AddResults(tab, results)
     if self._record_v8_object_stats:
       self._v8_object_stats_metric.Stop(page, tab)
       self._v8_object_stats_metric.AddResults(tab, results)
 
     if self._report_speed_index:
       def SpeedIndexIsFinished():
         return self._speedindex_metric.IsFinished(tab)
       util.WaitFor(SpeedIndexIsFinished, 60)
       self._speedindex_metric.Stop(page, tab)
       self._speedindex_metric.AddResults(
@@ skipping 11 matching lines @@
     # preserve any initial profile cache for as long as possible.
     # The second is that, if we did cold runs first, we'd have a transition
     # page set during which we wanted the run for each URL to both
     # contribute to the cold data and warm the catch for the following
     # warm run, and clearing the cache before the load of the following
     # URL would eliminate the intended warmup for the previous URL.
     return (self._has_loaded_page[url] >= self._cold_run_start_index)
 
   def results_are_the_same_on_every_page(self):
     return False