[system_health] Fix the lack of memory dump triggers on some user stories

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
@@ skipping 18 matching lines @@
       new_tab = tabs.New()
       new_tab.action_runner.Navigate(url)
 
     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):
+  def _DidLoadDocument(self, action_runner):
     for tab in action_runner.tab.browser.tabs:
       tab.Activate()
       tab.WaitForFrameToBeDisplayed()
 
 
 class MultiTabTypical24Story(MultiTabStory):
   """Load 24 different web sites in 24 tabs, then cycle through each tab."""
   NAME = 'multitab:misc:typical24'
   TAGS = [story_tags.TABS_SWITCHING]
   URL_LIST = [
@@ skipping 28 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