Remove startup_url from PageSet, we can now only specify startup_url on a Page.

tools/perf/page_sets/startup_pages.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.page import page as page_module
 from telemetry.page import page_set as page_set_module
 
 
 class StartedPage(page_module.Page):
 
   def __init__(self, url, startup_url, page_set):
-    super(StartedPage, self).__init__(url=url, page_set=page_set)
+    super(StartedPage, self).__init__(
+        url=url, page_set=page_set, startup_url=startup_url)
     self.archive_data_file = 'data/startup_pages.json'
-    self.startup_url = startup_url
 
   def RunNavigateSteps(self, action_runner):
     action_runner.Wait(10)
 
 class StartupPagesPageSet(page_set_module.PageSet):
 
   """ Pages for testing starting Chrome with a URL.
   Note that this file can't be used with record_wpr, since record_wpr requires
   a true navigate step, which we do not want for startup testing. Instead use
   record_wpr startup_pages_record to record data for this test.
   """
 
   def __init__(self):
     super(StartupPagesPageSet, self).__init__(
         archive_data_file='data/startup_pages.json',
         bucket=page_set_module.PARTNER_BUCKET)
 
     # Typical page.
     self.AddPage(StartedPage('about:blank', 'about:blank', self))
     # Typical page.
     self.AddPage(StartedPage('http://bbc.co.uk', 'http://bbc.co.uk', self))
     # Horribly complex page - stress test!
     self.AddPage(StartedPage('http://kapook.com', 'http://kapook.com', self))