Update perf page_set to use story_set

tools/perf/page_sets/service_worker.py

Index: tools/perf/page_sets/service_worker.py
diff --git a/tools/perf/page_sets/service_worker.py b/tools/perf/page_sets/service_worker.py
index 5ca067aeaf44c70fa44597da387287f1db5a8aa9..7f6027bbadd46ef77b190b307fab865082df254c 100644
--- a/tools/perf/page_sets/service_worker.py
+++ b/tools/perf/page_sets/service_worker.py
@@ -2,20 +2,19 @@
 # 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
-from telemetry.page import page_set as page_set
-
 
 archive_data_file_path = 'data/service_worker.json'
 
 
-class ServiceWorkerPageSet(page_set.PageSet):
+class ServiceWorkerPageSet(story.StorySet):
   """Page set of applications using ServiceWorker"""
 
   def __init__(self):
     super(ServiceWorkerPageSet, self).__init__(
         archive_data_file=archive_data_file_path,
-        bucket=page_set.PARTNER_BUCKET)
+        cloud_storage_bucket=story.PARTNER_BUCKET)
 
     # Why: the first application using ServiceWorker
     # 1st time: registration