[system-health] Add support for disabling individual stories on individual platforms

tools/perf/page_sets/system_health/browsing_stories.py

 # Copyright 2016 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 page_sets.system_health import platforms
 from page_sets.system_health import system_health_story
 
+from telemetry import decorators
+
 
 class _BrowsingStory(system_health_story.SystemHealthStory):
   """Abstract base class for browsing stories.
 
   A browsing story visits items on the main page. Subclasses provide
   CSS selector to identify the items and implement interaction using
   the helper methods of this class.
   """
 
   IS_SINGLE_PAGE_APP = False
@@ skipping 54 matching lines @@
     action_runner.Wait(self.ITEM_READ_TIME_IN_SECONDS)
     action_runner.RepeatableBrowserDrivenScroll(
         repeat_count=self.ITEM_SCROLL_REPEAT)
 
   def _ScrollMainPage(self, action_runner):
     action_runner.tab.WaitForDocumentReadyStateToBeComplete()
     action_runner.RepeatableBrowserDrivenScroll(
         repeat_count=self.MAIN_PAGE_SCROLL_REPEAT)
 
 
+# TODO(ulan): Enable this story on mobile once it uses less memory and does not
+# crash with OOM.
+@decorators.Disabled('android')
 class CnnStory(_NewsBrowsingStory):
   """The second top website in http://www.alexa.com/topsites/category/News"""
   NAME = 'browse:news:cnn'
   URL = 'http://edition.cnn.com/'
   ITEM_SELECTOR = '.cd__content > h3 > a'
   ITEMS_TO_VISIT = 2
-  # TODO(ulan): Enable this story on mobile once it uses less memory and
-  # does not crash with OOM.
-  SUPPORTED_PLATFORMS = platforms.DESKTOP_ONLY
 
 
 class FacebookMobileStory(_NewsBrowsingStory):
   NAME = 'browse:social:facebook'
   URL = 'https://www.facebook.com/rihanna'
   ITEM_SELECTOR = 'article ._5msj'
   # We scroll further than usual so that Facebook fetches enough items
   # (crbug.com/631022)
   MAIN_PAGE_SCROLL_REPEAT = 1
   SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
@@ skipping 43 matching lines @@
 
 
 class NytimesDesktopStory(_NewsBrowsingStory):
   """The third top website in http://www.alexa.com/topsites/category/News"""
   NAME = 'browse:news:nytimes'
   URL = 'http://www.nytimes.com'
   ITEM_SELECTOR = '.story-heading > a'
   SUPPORTED_PLATFORMS = platforms.DESKTOP_ONLY
 
 
+# Desktop qq.com opens a news item in a separate tab, for which the back button
+# does not work. Mobile qq.com is disabled due to crbug.com/627166.
+@decorators.Disabled('all')
 class QqMobileStory(_NewsBrowsingStory):
   NAME = 'browse:news:qq'
   URL = 'http://news.qq.com'
-  # Desktop qq.com opens a news item in a separate tab, for which the back
-  # button does not work.
-  # Mobile qq.com is disabled due to crbug.com/627166
   ITEM_SELECTOR = '.list .full a'
-  SUPPORTED_PLATFORMS = platforms.NO_PLATFORMS
+  SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
 
 
 class RedditDesktopStory(_NewsBrowsingStory):
   """The top website in http://www.alexa.com/topsites/category/News"""
   NAME = 'browse:news:reddit'
   URL = 'https://www.reddit.com/r/news/top/?sort=top&t=week'
   ITEM_SELECTOR = '.thing .title > a'
   SUPPORTED_PLATFORMS = platforms.DESKTOP_ONLY
 
 
@@ skipping 101 matching lines @@
   URL = 'https://www.youtube.com/watch?v=QGfhS1hfTWw&autoplay=false'
   ITEM_SELECTOR = '.yt-uix-simple-thumb-related'
   SUPPORTED_PLATFORMS = platforms.DESKTOP_ONLY
   IS_SINGLE_PAGE_APP = True
   # A longer view time allows videos to load and play.
   ITEM_VIEW_TIME_IN_SECONDS = 5
   ITEMS_TO_VISIT = 8
   ITEM_SELECTOR_INDEX = 3
 
 
-class FacebookPhotosMediaStory(_MediaBrowsingStory):
+class FacebookPhotosMobileStory(_MediaBrowsingStory):
   NAME = 'browse:media:facebook_photos'
   URL = (
       'https://m.facebook.com/rihanna/photos/a.207477806675.138795.10092511675/10153911739606676/?type=3&source=54&ref=page_internal')
   ITEM_SELECTOR = '._57-r.touchable'
   SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
   IS_SINGLE_PAGE_APP = True
   ITEM_SELECTOR_INDEX = 0
 
 
 class FacebookPhotosDesktopStory(_MediaBrowsingStory):
   NAME = 'browse:media:facebook_photos'
   URL = (
       'https://www.facebook.com/rihanna/photos/a.207477806675.138795.10092511675/10153911739606676/?type=3&theater')
   ITEM_SELECTOR = '.snowliftPager.next'
   # Recording currently does not work. The page gets stuck in the
   # theater viewer.
   SUPPORTED_PLATFORMS = platforms.NO_PLATFORMS
   IS_SINGLE_PAGE_APP = True