[system health] Add desktop browsing story for facebook and change url of twitter story.

tools/perf/page_sets/system_health/browsing_stories.py

Index: tools/perf/page_sets/system_health/browsing_stories.py
diff --git a/tools/perf/page_sets/system_health/browsing_stories.py b/tools/perf/page_sets/system_health/browsing_stories.py
index 072b2f42f831ef8f72ed15a57747046c5b55de3b..37389f5f0c242c605ebe698b0a02de6f2be09dc7 100644
--- a/tools/perf/page_sets/system_health/browsing_stories.py
+++ b/tools/perf/page_sets/system_health/browsing_stories.py
@@ -94,11 +94,17 @@ class FacebookMobileStory(_NewsBrowsingStory):
   NAME = 'browse:social:facebook'
   URL = 'https://www.facebook.com/rihanna'
   ITEM_SELECTOR = 'article ._5msj'
-  # Facebook on desktop is not interesting because it embeds post comments
-  # directly in the main timeline.

[ulan, 2016/07/18 11:07:26]

The comment was not entirely correct: photo posts are opened in pop-up window.

   SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
 
 
+class FacebookDesktopStory(_NewsBrowsingStory):
+  NAME = 'browse:social:facebook'
+  URL = 'https://www.facebook.com/rihanna'
+  ITEM_SELECTOR = '._4-eo'
+  IS_SINGLE_PAGE_APP = True
+  SUPPORTED_PLATFORMS = platforms.DESKTOP_ONLY
+
+
 class HackerNewsStory(_NewsBrowsingStory):
   NAME = 'browse:news:hackernews'
   URL = 'https://news.ycombinator.com'
@@ -152,14 +158,14 @@ class RedditMobileStory(_NewsBrowsingStory):
 
 class TwitterMobileStory(_NewsBrowsingStory):
   NAME = 'browse:social:twitter'
-  URL = 'https://www.twitter.com/justinbieber?skip_interstitial=true'
+  URL = 'https://www.twitter.com/nasa'

[ulan, 2016/07/18 11:07:26]

It is difficult to get work appropriate twitter comment contents with the old
url :)

   ITEM_SELECTOR = '.Tweet-text'
   SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
 
 
 class TwitterDesktopStory(_NewsBrowsingStory):
   NAME = 'browse:social:twitter'
-  URL = 'https://www.twitter.com/justinbieber?skip_interstitial=true'
+  URL = 'https://www.twitter.com/nasa'
   IS_SINGLE_PAGE_APP = True
   ITEM_SELECTOR = '.tweet-text'
   SUPPORTED_PLATFORMS = platforms.DESKTOP_ONLY