[Telemetry] Add support for capturing V8 object stats to Telemetry.

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
 collections are performed in between the page loads (in the beforeunload event).
 This extra garbage collection time is not included in the measurement times.
 
 Finally, various memory and IO statistics are gathered at the very end of
 cycling all pages.
 """
 
 import collections
 import os
 import sys
 
 from metrics import io
 from metrics import memory
+from metrics import v8_object_stats
 from telemetry.core import util
 from telemetry.page import page_measurement
 
 class PageCycler(page_measurement.PageMeasurement):
   def __init__(self, *args, **kwargs):
     super(PageCycler, self).__init__(*args, **kwargs)
 
     with open(os.path.join(os.path.dirname(__file__),
                            'page_cycler.js'), 'r') as f:
       self._page_cycler_js = f.read()
 
+    self._record_v8_object_stats = False
+
     self._memory_metric = None
+    self._v8_object_stats_metric = None
     self._number_warm_runs = None
     self._cold_runs_requested = False
     self._has_loaded_page = collections.defaultdict(int)
 
   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.
     # TODO: Remove this after transition to run_benchmark.
     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('--v8-object-stats',
+        action='store_true',
+        help='Enable detailed V8 object statistics.')
+
     parser.add_option('--cold-load-percent', type='int', default=0,
                       help='%d of page visits for which a cold load is forced')
 
+
   def DidStartBrowser(self, browser):
     """Initialize metrics once right after the browser has been launched."""
     self._memory_metric = memory.MemoryMetric(browser)
+    if self._record_v8_object_stats:
+      self._v8_object_stats_metric = v8_object_stats.V8ObjectStatsMetric()
 
   def DidStartHTTPServer(self, tab):
     # 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()
 
   def DidNavigateToPage(self, page, tab):
     self._memory_metric.Start(page, tab)
+    if self._record_v8_object_stats:
+      self._v8_object_stats_metric.Start(page, tab)
 
   def CustomizeBrowserOptions(self, options):
     memory.MemoryMetric.CustomizeBrowserOptions(options)
     io.IOMetric.CustomizeBrowserOptions(options)
     options.AppendExtraBrowserArg('--js-flags=--expose_gc')
 
+    if options.v8_object_stats:
+      self._record_v8_object_stats = True
+      v8_object_stats.V8ObjectStatsMetric.CustomizeBrowserOptions(options)
+
     # A disk cache bug causes some page cyclers to hang on mac.
     # TODO(tonyg): Re-enable these tests when crbug.com/268646 is fixed.
     if (sys.platform == 'darwin' and
         (sys.argv[-1].endswith('/intl_hi_ru.json') or
          sys.argv[-1].endswith('/tough_layout_cases.json') or
          sys.argv[-1].endswith('/typical_25.json'))):
       print '%s is currently disabled on mac. Skipping test.' % sys.argv[-1]
       sys.exit(0)
 
     # Handle requests for cold cache runs
@@ skipping 30 matching lines @@
                   'warm_times')
 
     results.Add('page_load_time', 'ms',
                 int(float(tab.EvaluateJavaScript('__pc_load_time'))),
                 chart_name=chart_name)
 
     self._has_loaded_page[page.url] += 1
 
     self._memory_metric.Stop(page, tab)
     self._memory_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)
 
   def DidRunTest(self, tab, results):
     self._memory_metric.AddSummaryResults(results)
     io.IOMetric().AddSummaryResults(tab, results)
 
   def ShouldRunCold(self, url):
     # We do the warm runs first for two reasons.  The first is so we can
     # 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._number_warm_runs + 1
 
   def results_are_the_same_on_every_page(self):
     return not self._cold_runs_requested