All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=905817

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=f52d3b3f5e3cd054e1efa470452d9170d055337d37b9094f3d789cb12a3bca13


Bot(s) for this bug's original alert(s):

Android Nexus5 Perf
android-nexus5x-perf
mac-10_12_laptop_low_end-perf
mac-10_13_laptop_high_end-perf

system_health.common_desktop - Benchmark documentation link:
  https://bit.ly/system-health-benchmarks

system_health.memory_mobile - Benchmark documentation link:
  https://bit.ly/system-health-benchmarks

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/15bfbebbe40000

📍 Found a significant difference after 1 commit.
https://pinpoint-dot-chromeperf.appspot.com/job/15bfbebbe40000

Adding GooglePlayStoreDesktop system_health media browsing story. by mbarowsky@chromium.org
https://chromium.googlesource.com/chromium/src/+/28c2d1ac39edb99342b900bf69142beee070936e
timeToFirstPaint: 268.5 → 200.6 (-67.9)

Understanding performance regressions:
  http://g.co/ChromePerformanceRegressions

Benchmark documentation link:
  https://bit.ly/system-health-benchmarks

That commit was for adding a system_health Desktop story, so it is expected to increase memory usage for Desktop. In the performance graphs, I don't see a negative effect to memory_mobile.

@kouhei Can I mark this as "WontFix"?

Yes, looks like there is no negative impact.  I think something went wrong with the alert UI.