[perf] Add browse:news:reddit:2018 system health story

Bug: 878390
Change-Id: Ibdc7919fb7658858b16227976e7e74c9eb74a007
Reviewed-on: https://chromium-review.googlesource.com/c/1261448Reviewed-by: Juan Antonio Navarro Pérez <perezju@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597092}

tools/perf/page_sets/data/system_health_desktop.json

@@ -45,6 +45,9 @@
         "browse:news:reddit": {
             "DEFAULT": "system_health_desktop_016.wprgo"
         },
+        "browse:news:reddit:2018": {
+            "DEFAULT": "system_health_desktop_907087980d.wprgo"
+        },
         "browse:search:google": {
             "DEFAULT": "system_health_desktop_037.wprgo"
         },

tools/perf/page_sets/data/system_health_desktop_095d91e4f1.wprgo.sha1

+095d91e4f10176ea40eced02a9e656a5e131e3c8
\ No newline at end of file

tools/perf/page_sets/data/system_health_desktop_907087980d.wprgo.sha1

+907087980d52d972104ce9b71ab50d7a8b6a52e0
\ No newline at end of file

tools/perf/page_sets/system_health/browsing_stories.py

@@ -247,6 +247,16 @@ class RedditDesktopStory(_ArticleBrowsingStory):
   TAGS = [story_tags.YEAR_2016]
 
 
+class RedditDesktopStory2018(_ArticleBrowsingStory):
+  """The top website in http://www.alexa.com/topsites/category/News"""
+  NAME = 'browse:news:reddit:2018'
+  URL = 'https://www.reddit.com/r/news/top/?sort=top&t=week'
+  IS_SINGLE_PAGE_APP = True
+  ITEM_SELECTOR = 'article'
+  SUPPORTED_PLATFORMS = platforms.DESKTOP_ONLY
+  TAGS = [story_tags.YEAR_2018]
+
+
 class RedditMobileStory(_ArticleBrowsingStory):
   """The top website in http://www.alexa.com/topsites/category/News"""
   NAME = 'browse:news:reddit'