Add a history state update example to key_silk_cases

tools/perf/page_sets/key_silk_cases.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.
 # pylint: disable=W0401,W0614
 from telemetry.page.actions.all_page_actions import *
 from telemetry.page import page as page_module
 from telemetry.page import page_set as page_set_module
 
 
 class KeySilkCasesPage(page_module.Page):
@@ skipping 571 matching lines @@
   def RunSmoothness(self, action_runner):
     for i in xrange(9):
       button_func = ('document.getElementById("demo").$.'
                      'buttons.children[%d]') % i
       interaction = action_runner.BeginInteraction(
             'Action_TapAction', is_smooth=True)
       action_runner.TapElement(element_function=button_func)
       action_runner.Wait(1)
       interaction.End()
 
+
+class UpdateHistoryState(KeySilkCasesPage):
+
+  """ Why: Modern apps often update history state, which currently is janky."""
+
+  def __init__(self, page_set):
+    super(UpdateHistoryState, self).__init__(
+      url='file://key_silk_cases/pushState.html',
+      page_set=page_set)
+
+  def RunNavigateSteps(self, action_runner):
+    action_runner.NavigateToPage(self)
+    action_runner.ExecuteJavaScript('''
+        window.requestAnimationFrame(function() {
+            window.__history_state_loaded = true;
+          });
+        ''')
+    action_runner.WaitForJavaScriptCondition(
+        'window.__history_state_loaded == true;')
+
+  def RunSmoothness(self, action_runner):
+    interaction = action_runner.BeginInteraction('animation_interaction',
+        is_smooth=True)
+    action_runner.Wait(5) # JS runs the animation continuously on the page
+    interaction.End()
+
+
 class KeySilkCasesPageSet(page_set_module.PageSet):
 
   """ Pages hand-picked for project Silk. """
 
   def __init__(self):
     super(KeySilkCasesPageSet, self).__init__(
       credentials_path='data/credentials.json',
       user_agent_type='mobile',
       archive_data_file='data/key_silk_cases.json',
       bucket=page_set_module.PARTNER_BUCKET)
@@ skipping 18 matching lines @@
     self.AddPage(Page18(self))
     self.AddPage(Page19(self))
     self.AddPage(Page20(self))
     self.AddPage(Page21(self))
     self.AddPage(Page22(self))
     self.AddPage(Page23(self))
     self.AddPage(Page24(self))
     self.AddPage(Page25(self))
     self.AddPage(Page26(self))
     self.AddPage(SVGIconRaster(self))
+    self.AddPage(UpdateHistoryState(self))