Support flag --tabset-repeat on benchmark tab_switching

tools/perf/page_sets/system_health/multi_tab_stories.py

 # Copyright 2017 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 py_utils
 import logging
 
 from page_sets.system_health import system_health_story
 from page_sets.system_health import story_tags
 from page_sets.system_health import platforms
 
 from telemetry import benchmark
 
 
 class MultiTabStory(system_health_story.SystemHealthStory):
   ABSTRACT_STORY = True
 
+  def __init__(self, story_set, take_memory_measurement, tabset_repeat=1):
+    super(MultiTabStory, self).__init__(story_set, take_memory_measurement)
+    self._tabset_repeat = tabset_repeat
+
   def RunNavigateSteps(self, action_runner):
     tabs = action_runner.tab.browser.tabs
 
     # No need to create the first tab as there is already one
     # when the browser is ready,
-    if self.URL_LIST:
-      action_runner.Navigate(self.URL_LIST[0])
-    for url in self.URL_LIST[1:]:
+    url_list = self.URL_LIST * self._tabset_repeat
+    if url_list:
+      action_runner.Navigate(url_list[0])
+    for url in url_list[1:]:
       new_tab = tabs.New()
       new_tab.action_runner.Navigate(url)
 
-    for i, url in enumerate(self.URL_LIST):
+    for i, url in enumerate(url_list):
       try:
         tabs[i].action_runner.WaitForNetworkQuiescence()
       except py_utils.TimeoutException:
         logging.warning('WaitForNetworkQuiescence() timeout, url[%d]: %s'
                         % (i, url))
 
   def RunPageInteractions(self, action_runner):
     for tab in action_runner.tab.browser.tabs:
       tab.Activate()
       tab.WaitForFrameToBeDisplayed()
@@ skipping 35 matching lines @@
      '1837448?brand=none&tm_link=tm_homeA_rc_name2'),
     # pylint: disable=line-too-long
     'http://www.theverge.com/2013/3/5/4061684/inside-ted-the-smartest-bubble-in-the-world',
     'http://www.airbnb.com/',
     'http://www.ign.com/',
     # Why: Alexa health #25
     'http://www.fda.gov',
   ]
   URL = URL_LIST[0]
   SUPPORTED_PLATFORMS = platforms.DESKTOP_ONLY