Update perf page_set to use story_set

tools/perf/page_sets/flash_energy_cases.py

Index: tools/perf/page_sets/flash_energy_cases.py
diff --git a/tools/perf/page_sets/flash_energy_cases.py b/tools/perf/page_sets/flash_energy_cases.py
index c711a9f3f58a957dbdb413de9a8af8cf3131ba0b..f1d6d49f55d29c09f52de1b8c9d757bfce000c89 100644
--- a/tools/perf/page_sets/flash_energy_cases.py
+++ b/tools/perf/page_sets/flash_energy_cases.py
@@ -1,8 +1,8 @@
 # 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 import story
 from telemetry.page import page as page_module
-from telemetry.page import page_set as page_set_module
 from telemetry.page import shared_page_state
 
 
@@ -15,14 +15,14 @@ class FlashEnergyCasesPage(page_module.Page):
     self.archive_data_file = 'data/flash_energy_cases.json'
 
 
-class FlashEnergyCasesPageSet(page_set_module.PageSet):
+class FlashEnergyCasesPageSet(story.StorySet):
 
   """ Pages with flash heavy content. """
 
   def __init__(self):
     super(FlashEnergyCasesPageSet, self).__init__(
       archive_data_file='data/flash_energy_cases.json',
-      bucket=page_set_module.PARTNER_BUCKET)
+      cloud_storage_bucket=story.PARTNER_BUCKET)
 
     urls_list = [
         # pylint: disable=C0301