Update perf page_set to use story_set

tools/perf/page_sets/chrome_signin.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 page_sets.login_helpers import chrome_login
+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
-
-from page_sets.login_helpers import chrome_login
 
 
 class ChromeSigninPage(page_module.Page):
   """A page that signs in a user to Chrome."""
 
   def __init__(self, page_set):
     super(ChromeSigninPage, self).__init__(
         url='chrome://signin-internals',
         page_set=page_set,
         credentials_path='data/chrome_signin_credentials.json',
-        credentials_bucket=page_set_module.INTERNAL_BUCKET,
+        credentials_bucket=story.INTERNAL_BUCKET,
         shared_page_state_class=shared_page_state.SharedDesktopPageState)
 
   def RunPageInteractions(self, action_runner):
     # Use page.credentials_path because it is automatically translated into a
     # full path relative to the page.
     chrome_login.LoginChromeAccount(action_runner, 'chrome',
         credentials_path=self.credentials_path)
 
 
-class ChromeSigninPageSet(page_set_module.PageSet):
+class ChromeSigninPageSet(story.StorySet):
 
   def __init__(self):
     super(ChromeSigninPageSet, self).__init__(
         archive_data_file='data/chrome_signin_archive.json',
-        bucket=page_set_module.INTERNAL_BUCKET)
+        cloud_storage_bucket=story.INTERNAL_BUCKET)
     self.AddUserStory(ChromeSigninPage(self))