All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=752414

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=f75fe1ab88438525803526a5b57ac6c3c3969789aab4f226b021b4c1d35db640


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

chromium-rel-mac12

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8972207462819438256

=== Auto-CCing suspected CL author xunjieli@chromium.org ===

Hi xunjieli@chromium.org, the bisect results pointed to your CL, please take a look at the
results.


=== BISECT JOB RESULTS ===
Perf regression found with culprit

Suspected Commit
  Author : Helen Li
  Commit : 05ee1dbfaf0aa7c03b9ea2040f0345277042d0f1
  Date   : Mon Jul 31 13:24:01 2017
  Subject: [wpr-go] Switch system_health_desktop.json to use go

Bisect Details
  Configuration: mac_10_12_perf_bisect
  Benchmark    : system_health.memory_desktop
  Metric       : memory:chrome:all_processes:reported_by_chrome:v8:effective_size_avg/load_social/load_social_instagram
  Change       : 74.36% | 12699769.3333 -> 3255776.0

Revision             Result                   N
chromium@490749      12699769 +- 204377       6      good
chromium@490750      12550608 +- 61712.5      6      good
chromium@490751      3254332 +- 8035.16       6      bad       <--
chromium@490752      3254375 +- 7908.54       6      bad
chromium@490754      3255792 +- 472.339       6      bad
chromium@490759      3255765 +- 473.647       6      bad
chromium@490769      3256303 +- 337.789       6      bad
chromium@490788      3255660 +- 127.373       6      bad
chromium@490826      3255776 +- 335.428       6      bad

Please refer to the following doc on diagnosing memory regressions:
  https://chromium.googlesource.com/chromium/src/+/master/docs/memory-infra/memory_benchmarks.md

To Run This Test
  src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=load.social.instagram system_health.memory_desktop

More information on addressing performance regressions:
  http://g.co/ChromePerformanceRegressions

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8972207462819438256


For feedback, file a bug with component Speed>Bisection

Thanks for filing the alert. 
Yes, something broke. This is fixed in last night's catapult roll (eb34528a8b674bea3e27dd45496e7d2201a0ba05). 

The metrics are back to the original values. I will keep the bug open to keep track of the graphs.

Thanks, I confirm that this is fixed in 357e1deefca78c61e457f340270c9cd6f38321f5. All grouped metrics are back at their original value before the wpr-go switch (05ee1dbfaf0aa7c03b9ea2040f0345277042d0f1).