Update perf page_set to use story_set

tools/perf/page_sets/simple_mobile_sites_fling.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.
 from page_sets import fling_gesture_supported_shared_state
-
+from telemetry import story
 from telemetry.page import page as page_module
-from telemetry.page import page_set as page_set_module
 
 
 class SimpleFlingPage(page_module.Page):
 
   def __init__(self, url, page_set):
     super(SimpleFlingPage, self).__init__(
         url=url,
         page_set=page_set,
         credentials_path='data/credentials.json',
         shared_page_state_class=(fling_gesture_supported_shared_state\
             .FlingGestureSupportedSharedState))
     self.archive_data_file = 'data/simple_mobile_sites.json'
 
   def RunNavigateSteps(self, action_runner):
     super(SimpleFlingPage, self).RunNavigateSteps(action_runner)
     # TODO(epenner): Remove this wait (http://crbug.com/366933)
     action_runner.Wait(5)
 
   def RunPageInteractions(self, action_runner):
     with action_runner.CreateGestureInteraction('FlingAction'):
       # Swiping up induces a downward fling, and 500 pixels of touch scrolling
       # runway ensures consistent fling velocities.
       action_runner.SwipePage(direction='up',
                               distance='500',
                               speed_in_pixels_per_second=5000)
 
-class SimpleMobileSitesFlingPageSet(page_set_module.PageSet):
+class SimpleMobileSitesFlingPageSet(story.StorySet):
 
   """ Simple mobile sites """
 
   def __init__(self):
     super(SimpleMobileSitesFlingPageSet, self).__init__(
       archive_data_file='data/simple_mobile_sites.json',
-      bucket=page_set_module.PUBLIC_BUCKET)
+      cloud_storage_bucket=story.PUBLIC_BUCKET)
 
     fling_page_list = [
       # Why: Scrolls moderately complex pages (up to 60 layers)
       'http://www.ebay.co.uk/',
       'https://www.flickr.com/',
       'http://www.apple.com/mac/',
       'http://www.nyc.gov',
       'http://m.nytimes.com/'
     ]
 
     for url in fling_page_list:
       self.AddUserStory(SimpleFlingPage(url, self))
-