Disable system_health.memory_desktop/browse:media:pinterest.

The test was observed to be flaky.

Bug: 870852
Change-Id: I3163111ba26e30d0864ff3a52a1ab21e64137725
TBR: nednguyen@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/1163678Reviewed-by: Balazs Engedy <engedy@chromium.org>
Commit-Queue: Balazs Engedy <engedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580899}

tools/perf/expectations.config

@@ -231,6 +231,7 @@ crbug.com/837397 [ Linux ] system_health.memory_desktop/load_accessibility:shopp
 crbug.com/869118 [ Linux ] system_health.memory_desktop/long_running:tools:gmail-background [ Skip ]
 crbug.com/836447 [ ChromeOS ] system_health.memory_desktop/multitab:misc:typical24 [ Skip ]
 crbug.com/799734 [ Win ] system_health.memory_desktop/browse:media:tumblr [ Skip ]
+crbug.com/870852 [ Win ] system_health.memory_desktop/browse:media:pinterest [ Skip ]
 
 # Benchmark: system_health.memory_mobile
 crbug.com/787001 [ Android_Webview ] system_health.memory_mobile/load:media:soundcloud [ Skip ]