Update perf page_set to use story_set

tools/perf/page_sets/tough_video_cases.py

 # 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
 
 
 class ToughVideoCasesPage(page_module.Page):
 
   def __init__(self, url, page_set, labels=None):
     super(ToughVideoCasesPage, self).__init__(
         url=url, page_set=page_set, labels=labels)
 
   def LoopMixedAudio(self, action_runner):
     action_runner.PlayMedia(selector='#background_audio',
@@ skipping 475 matching lines @@
     super(Page36, self).__init__(
       url=('file://tough_video_cases/video.html?src='
            'smpte_3840x2160_60fps_vp9.webm'),
       page_set=page_set)
 
     self.add_browser_metrics = True
 
   def RunPageInteractions(self, action_runner):
     self.SeekBeforeAndAfterPlayhead(action_runner)
 
-class ToughVideoCasesPageSet(page_set_module.PageSet):
+class ToughVideoCasesPageSet(story.StorySet):
 
   """
   Description: Video Stack Perf benchmark
   """
   def __init__(self):
     super(ToughVideoCasesPageSet, self).__init__(
-            bucket=page_set_module.PARTNER_BUCKET)
+            cloud_storage_bucket=story.PARTNER_BUCKET)
 
     self.AddUserStory(Page1(self))
     self.AddUserStory(Page2(self))
     self.AddUserStory(Page3(self))
     self.AddUserStory(Page4(self))
     self.AddUserStory(Page5(self))
     self.AddUserStory(Page6(self))
     self.AddUserStory(Page7(self))
     self.AddUserStory(Page8(self))
     self.AddUserStory(Page9(self))
@@ skipping 17 matching lines @@
     self.AddUserStory(Page27(self))
     self.AddUserStory(Page28(self))
     self.AddUserStory(Page29(self))
     self.AddUserStory(Page30(self))
     self.AddUserStory(Page31(self))
     self.AddUserStory(Page32(self))
     self.AddUserStory(Page33(self))
     self.AddUserStory(Page34(self))
     self.AddUserStory(Page35(self))
     self.AddUserStory(Page36(self))