Update perf page_set to use story_set

tools/perf/page_sets/idle_multi_tab_cases.py

 # Copyright 2015 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 os
 
+from page_sets import top_7_stress
+from page_sets import top_pages
+from telemetry import story
 from telemetry.page import shared_page_state
-from telemetry.page import page_set as page_set_module
-
-from page_sets import top_pages
-from page_sets import top_7_stress
 
 
 def _SpawnTab(action_runner):
   return action_runner.EvaluateJavaScript('__telemetry_spawn_tab()')
 
 
 def _CloseTab(action_runner, tab):
   action_runner.EvaluateJavaScript('__telemetry_close_tab(' + str(tab) + ')')
 
 
@@ skipping 18 matching lines @@
       for tab in xrange(MAX_TABS):
         tabs[tab] = _SpawnTab(action_runner)
       action_runner.Wait(20)
       # Quickly close tabs.
       for tab in xrange(MAX_TABS):
         _CloseTab(action_runner, tabs[tab])
       action_runner.Wait(30)
   return DerivedIdleMultiTabPage
 
 
-class IdleMultiTabCasesPageSet(page_set_module.PageSet):
+class IdleMultiTabCasesPageSet(story.StorySet):
 
   """ Pages for testing GC efficiency on idle pages. """
 
   def __init__(self):
     super(IdleMultiTabCasesPageSet, self).__init__(
         archive_data_file='data/top_25.json',
-        bucket=page_set_module.PARTNER_BUCKET)
+        cloud_storage_bucket=story.PARTNER_BUCKET)
     with open(os.path.join(os.path.dirname(__file__),
               'idle_multi_tab_cases.js')) as f:
       base_js = f.read()
     self.AddUserStory(
         _CreateIdleMultiTabPageClass(top_pages.GoogleDocPage, base_js)
         (self, shared_page_state.SharedDesktopPageState))
     self.AddUserStory(
         _CreateIdleMultiTabPageClass(top_7_stress.GooglePlusPage, base_js)
         (self))