BrowserOptions.extra_browser_args is now a set.

tools/perf/metrics/v8_object_stats.py

 # Copyright 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
 import logging
 
 from metrics import Metric
 
 _COUNTER_NAMES = [
@@ skipping 142 matching lines @@
   It does this by enabling the --track_gc_object_stats flag on V8 and reading
   these statistics from the StatsTableMetric.
   """
 
   def __init__(self):
     super(V8ObjectStatsMetric, self).__init__()
     self._results = None
 
   @classmethod
   def CustomizeBrowserOptions(cls, options):
-    options.AppendExtraBrowserArg('--enable-stats-table')
-    options.AppendExtraBrowserArg('--enable-benchmarking')
-    options.AppendExtraBrowserArg(
-        '--js-flags=--track_gc_object_stats --expose_gc')
-    # TODO(rmcilroy): This is needed for --enable-stats-table.  Update once
-    # https://codereview.chromium.org/22911027/ lands.
-    options.AppendExtraBrowserArg('--no-sandbox')
+    options.AppendExtraBrowserArgs([
+        '--enable-stats-table',
+        '--enable-benchmarking',
+        '--js-flags=--track_gc_object_stats --expose_gc',
+        # TODO(rmcilroy): This is needed for --enable-stats-table.  Update once
+        # https://codereview.chromium.org/22911027/ lands.
+        '--no-sandbox'
+    ])
 
   @staticmethod
   def GetV8StatsTable(tab, counters=None):
     counters = counters or _COUNTER_NAMES
 
     return tab.EvaluateJavaScript("""
      (function(counters) {
        var results = {};
        if (!window.chrome || !window.chrome.benchmarking)
         return results;
@@ skipping 13 matching lines @@
     """Get the values in the stats table after the page is loaded."""
     self._results = V8ObjectStatsMetric.GetV8StatsTable(tab)
     if not self._results:
       logging.warning('No V8 object stats from website: ' + page.display_name)
 
   def AddResults(self, tab, results):
     """Add results for this page to the results object."""
     assert self._results != None, 'Must call Stop() first'
     for counter_name in self._results:
       results.Add(counter_name, 'kb', self._results[counter_name] / 1024.0)