All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=752407

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=ef164b71209d50205619f912ace08770ac3162478d5ca77ad8da9eb9563181c2


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

chromium-rel-win10

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8972207597342498112

=== 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: winx64_10_perf_bisect
  Benchmark    : system_health.common_desktop
  Metric       : timeToFirstContentfulPaint_avg/browse_news/browse_news_reddit
  Change       : 26.94% | 901.579876543 -> 1049.88935185

Revision             Result                  N
chromium@490745      901.58 +- 672.512       9      good
chromium@490749      906.913 +- 696.593      9      good
chromium@490750      908.576 +- 775.137      9      good
chromium@490751      1135.86 +- 683.798      9      bad       <--
chromium@490753      1196.33 +- 953.387      9      bad
chromium@490760      1152.59 +- 800.914      6      bad
chromium@490774      1049.89 +- 56.3238      6      bad

To Run This Test
  src/tools/perf/run_benchmark -v --browser=release_x64 --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=browse.news.reddit system_health.common_desktop

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

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8972207597342498112


For feedback, file a bug with component Speed>Bisection

Thanks for filing this alert. 
I will go ahead and merge this with  Issue 751983  which tracks regressions in timeToFirstContentfulPaint_avg on desktop.