Add load:social:twitter:2019 system health story

This CL was created automatically with tools/perf/update_wpr script

R=perezju@chromium.org

Change-Id: Ib29f3bf0ea6a4a8a387c888304e02bd9e0c64578
Bug: 878390
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1816461
Auto-Submit: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Juan Antonio Navarro Pérez <perezju@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#698874}

tools/perf/page_sets/data/system_health_mobile.json

@@ -264,6 +264,9 @@
         "load:social:twitter": {
             "DEFAULT": "system_health_mobile_022.wprgo"
         },
+        "load:social:twitter:2019": {
+            "DEFAULT": "system_health_mobile_b29c43a85b.wprgo"
+        },
         "load:tools:docs": {
             "DEFAULT": "system_health_mobile_004.wprgo"
         },

tools/perf/page_sets/data/system_health_mobile_b29c43a85b.wprgo.sha1

+b29c43a85b06d0e24fbe82d99f4896471c13d9a2
\ No newline at end of file

tools/perf/page_sets/system_health/loading_stories.py

@@ -101,6 +101,14 @@ class LoadTwitterStory(_LoadingStory):
   # 'browse:social:twitter_infinite_scroll'
   SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
 
+class LoadTwitterMoibleStory2019(_LoadingStory):
+  NAME = 'load:social:twitter:2019'
+  URL = 'https://www.twitter.com/nasa'
+  TAGS = [story_tags.YEAR_2019]
+
+  # Desktop version is already covered by
+  # 'browse:social:twitter_infinite_scroll'
+  SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
 
 class LoadVkStory(_LoadingStory):
   NAME = 'load:social:vk'