Migrate PageSets to StorySets in buildbot page sets

tools/skp/page_sets/skia_gmailthread_desktop.py

Index: tools/skp/page_sets/skia_gmailthread_desktop.py
diff --git a/tools/skp/page_sets/skia_gmailthread_desktop.py b/tools/skp/page_sets/skia_gmailthread_desktop.py
index 7fefa2fd6fd79b38355305909191b5539c97e3e7..2f581740aa80926b989015923de764a3d1f53550 100644
--- a/tools/skp/page_sets/skia_gmailthread_desktop.py
+++ b/tools/skp/page_sets/skia_gmailthread_desktop.py
@@ -4,8 +4,9 @@
 # pylint: disable=W0401,W0614
 
 
+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
 
 
 class SkiaBuildbotDesktopPage(page_module.Page):
@@ -14,8 +15,8 @@ class SkiaBuildbotDesktopPage(page_module.Page):
     super(SkiaBuildbotDesktopPage, self).__init__(
         url=url,
         page_set=page_set,
-        credentials_path='data/credentials.json')
-    self.user_agent_type = 'desktop'
+        credentials_path='data/credentials.json',
+        shared_page_state_class=shared_page_state.SharedDesktopPageState)
     self.archive_data_file = 'data/skia_gmailthread_desktop.json'
     self.credentials = 'google'
 
@@ -27,13 +28,12 @@ class SkiaBuildbotDesktopPage(page_module.Page):
     action_runner.Wait(15)
 
 
-class SkiaGmailthreadDesktopPageSet(page_set_module.PageSet):
+class SkiaGmailthreadDesktopPageSet(story.StorySet):
 
   """ Pages designed to represent the median, not highly optimized web """
 
   def __init__(self):
     super(SkiaGmailthreadDesktopPageSet, self).__init__(
-      user_agent_type='desktop',
       archive_data_file='data/skia_gmailthread_desktop.json')
 
     urls_list = [