Make credential_path a page attribute instead of page_set attribute.

tools/perf/page_sets/tough_pinch_zoom_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.page import page as page_module
 from telemetry.page import page_set as page_set_module
 
 
 class ToughPinchZoomCasesPage(page_module.Page):
 
   def __init__(self, url, page_set, name=''):
-    super(ToughPinchZoomCasesPage, self).__init__(url=url, page_set=page_set,
-                                                  name=name)
-    self.credentials_path = 'data/credentials.json'
+    super(ToughPinchZoomCasesPage, self).__init__(
+        url=url, page_set=page_set, name=name,
+        credentials_path = 'data/credentials.json')
     self.user_agent_type = 'desktop'
     self.archive_data_file = 'data/tough_pinch_zoom_cases.json'
 
   def RunSmoothness(self, action_runner):
     interaction = action_runner.BeginGestureInteraction(
         'PinchAction', is_smooth=True)
     action_runner.PinchPage()
     interaction.End()
 
 
@@ skipping 215 matching lines @@
     action_runner.PinchElement(selector='#ya-content-apps')
     interaction.End()
 
 
 class ToughPinchZoomCasesPageSet(page_set_module.PageSet):
 
   """ Set of pages that are tricky to pinch-zoom """
 
   def __init__(self):
     super(ToughPinchZoomCasesPageSet, self).__init__(
-      credentials_path='data/credentials.json',
       user_agent_type='desktop',
       archive_data_file='data/tough_pinch_zoom_cases.json',
       bucket=page_set_module.PARTNER_BUCKET)
 
     self.AddPage(GoogleSearchPage(self))
     self.AddPage(GmailPage(self))
     self.AddPage(GoogleCalendarPage(self))
     self.AddPage(GoogleImageSearchPage(self))
     self.AddPage(GooglePlusPage(self))
     self.AddPage(YoutubePage(self))
@@ skipping 21 matching lines @@
 
     self.AddPage(YahooGamePage(self))
 
     # Why: #1 Alexa recreation
     self.AddPage(ToughPinchZoomCasesPage('http://booking.com', self))
 
     self.AddPage(YahooAnswersPage(self))
 
     # Why: #1 Alexa sports
     self.AddPage(ToughPinchZoomCasesPage('http://sports.yahoo.com/', self))