Update perf page_set to use story_set

tools/perf/page_sets/top_25_pages.py

Index: tools/perf/page_sets/top_25_pages.py
diff --git a/tools/perf/page_sets/top_25_pages.py b/tools/perf/page_sets/top_25_pages.py
index dcb1edcbff69297ee45b6b84d219baa90b66c055..0b82261566c6b135a376b933b8f4a3f41f32f3fe 100644
--- a/tools/perf/page_sets/top_25_pages.py
+++ b/tools/perf/page_sets/top_25_pages.py
@@ -1,21 +1,20 @@
 # 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 telemetry.page import shared_page_state
-from telemetry.page import page
-from telemetry.page import page_set
-
 from page_sets import top_pages
+from telemetry import story
+from telemetry.page import page
+from telemetry.page import shared_page_state
 
 
-class Top25PageSet(page_set.PageSet):
+class Top25PageSet(story.StorySet):
 
   """ Page set consists of top 25 pages with only navigation actions. """
 
   def __init__(self):
     super(Top25PageSet, self).__init__(
         archive_data_file='data/top_25.json',
-        bucket=page_set.PARTNER_BUCKET)
+        cloud_storage_bucket=story.PARTNER_BUCKET)
 
     shared_desktop_state = shared_page_state.SharedDesktopPageState
     self.AddUserStory(top_pages.GoogleWebSearchPage(self, shared_desktop_state))