Make credential_path a page attribute instead of page_set attribute.

tools/perf/page_sets/key_mobile_sites.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 KeyMobileSitesPage(page_module.Page):
 
   def __init__(self, url, page_set, name=''):
-    super(KeyMobileSitesPage, self).__init__(url=url, page_set=page_set,
-                                             name=name)
-    self.credentials_path = 'data/credentials.json'
+    super(KeyMobileSitesPage, self).__init__(
+        url=url, page_set=page_set, name=name,
+        credentials_path = 'data/credentials.json')
     self.user_agent_type = 'mobile'
     self.archive_data_file = 'data/key_mobile_sites.json'
 
   def RunSmoothness(self, action_runner):
     interaction = action_runner.BeginGestureInteraction(
         'ScrollAction', is_smooth=True)
     action_runner.ScrollPage()
     interaction.End()
 
   def RunRepaint(self, action_runner):
@@ skipping 427 matching lines @@
         distance_expr='document.body.scrollHeight - window.innerHeight')
     interaction.End()
 
 
 class KeyMobileSitesPageSet(page_set_module.PageSet):
 
   """ Key mobile sites """
 
   def __init__(self):
     super(KeyMobileSitesPageSet, self).__init__(
-      credentials_path='data/credentials.json',
       user_agent_type='mobile',
       archive_data_file='data/key_mobile_sites.json',
       bucket=page_set_module.PARTNER_BUCKET)
 
     self.AddPage(Page1(self))
     self.AddPage(Page2(self))
     self.AddPage(Page3(self))
     self.AddPage(Page4(self))
     self.AddPage(Page5(self))
     self.AddPage(Page6(self))
@@ skipping 67 matching lines @@
       ('http://www.baidu.com/s?wd=barack+obama&rsv_bp=0&rsv_spt=3&rsv_sug3=9&'
        'rsv_sug=0&rsv_sug4=3824&rsv_sug1=3&inputT=4920'),
       # Why: Top search engine
       'http://www.bing.com/search?q=sloths',
       # Why: Good example of poor initial scrolling
       'http://ftw.usatoday.com/2014/05/spelling-bee-rules-shenanigans'
     ]
 
     for url in urls_list:
       self.AddPage(KeyMobileSitesPage(url, self))