Disabling system_health.memory_mobile stories

system_health.memory_mobile/browser:media:youtube
system_health.memory_mobile/browse:new:cnn

TBR=charliea@chromium.org
NOTRY=true

Bug: 853190
Change-Id: Id51228dccae8dc8d1f03f608f03183b54c79eec6
Reviewed-on: https://chromium-review.googlesource.com/1102344Reviewed-by: Emily Hanley <eyaich@chromium.org>
Commit-Queue: Emily Hanley <eyaich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567630}

tools/perf/expectations.config

@@ -358,6 +358,8 @@ crbug.com/836447 [ ChromeOS ] system_health.memory_desktop/multitab:misc:typical
 crbug.com/799734 [ Win ] system_health.memory_desktop/browse:media:tumblr [ Skip ]
 
 # Benchmark: system_health.memory_mobile
+crbug.com/853190 [ Android_Webview ] system_health.memory_mobile/browse:media:youtube [ Skip ]
+crbug.com/853190 [ Android_Webview ] system_health.memory_mobile/browse:news:cnn [ Skip ]
 crbug.com/787001 [ Android_Webview ] system_health.memory_mobile/load:media:soundcloud [ Skip ]
 [ Android_Webview ] system_health.memory_mobile/browse:chrome:newtab [ Skip ]
 crbug.com/847786 [ Android_One ] system_health.memory_mobile/browse:chrome:newtab [ Skip ]