[tools/perf] Make pages in typical_25 page_set to wait for load event to triggered

tools/perf/page_sets/typical_25.py

 # Copyright 2014 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 shutil
 
 from profile_creators import profile_generator
 from telemetry.page import page as page_module
 from telemetry.page import cache_temperature as cache_temperature_module
 from telemetry.page import shared_page_state
@@ skipping 32 matching lines @@
       shared_page_state_class=shared_page_state.SharedDesktopPageState,
       cache_temperature=None):
     super(Typical25Page, self).__init__(
         url=url, page_set=page_set,
         shared_page_state_class=shared_page_state_class,
         cache_temperature=cache_temperature)
     self._run_no_page_interactions = run_no_page_interactions
 
   def RunPageInteractions(self, action_runner):
     if self._run_no_page_interactions:
+      action_runner.WaitForJavaScriptCondition(
+          'performance.timing.loadEventStart > 0')
       return
     with action_runner.CreateGestureInteraction('ScrollAction'):
       action_runner.ScrollPage()
 
 
 class Typical25PageSet(story.StorySet):
 
   """ Pages designed to represent the median, not highly optimized web """
 
   def __init__(self, run_no_page_interactions=False,
@@ skipping 43 matching lines @@
       'http://www.airbnb.com/',
       'http://www.ign.com/',
       # Why: Alexa health #25
       'http://www.fda.gov',
     ]
 
     for url in urls_list:
       for temp in cache_temperatures:
         self.AddStory(page_class(
           url, self, run_no_page_interactions, cache_temperature=temp))