Update perf page_set to use story_set

tools/perf/page_sets/profile_safe_urls.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.
 from profile_creators import profile_safe_url_list
+from telemetry import story
+from telemetry.page import page as page_module
 from telemetry.page import shared_page_state
-from telemetry.page import page as page_module
-from telemetry.page import page_set as page_set_module
 
 
 class ProfileSafeUrlPage(page_module.Page):
   def __init__(self, url, page_set):
     super(ProfileSafeUrlPage, self).__init__(
         url=url,
         page_set = page_set,
         shared_page_state_class=shared_page_state.SharedDesktopPageState,
         credentials_path = 'data/credentials.json')
     self.credentials = 'google'
 
 
-class ProfileSafeUrlsPageSet(page_set_module.PageSet):
+class ProfileSafeUrlsPageSet(story.StorySet):
   """Safe urls used for profile generation."""
 
   def __init__(self):
     super(ProfileSafeUrlsPageSet, self).__init__(
       archive_data_file='data/profile_safe_urls.json',
-      bucket=page_set_module.PARTNER_BUCKET)
+      cloud_storage_bucket=story.PARTNER_BUCKET)
 
     # Only use the first 500 urls to prevent the .wpr files from getting too
     # big.
     safe_urls = profile_safe_url_list.GetShuffledSafeUrls()[0:500]
     for safe_url in safe_urls:
       self.AddUserStory(ProfileSafeUrlPage(safe_url, self))