All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=753971

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=f9f568fb046f13991a3fa46e635076b65bfe44c5abb562068cbec30bb6a96c8a


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

android-nexus5X

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8971703850856762320

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

Hi yukishiino@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 : Yuki Shiino
  Commit : e4d81dae1158bddcd44345329296df6ba95e34dd
  Date   : Wed Aug 02 07:30:06 2017
  Subject: v8binding: Refactors MutationObserver and MutationCallback.

Bisect Details
  Configuration: android_nexus5X_perf_bisect
  Benchmark    : system_health.memory_mobile
  Metric       : memory:chrome:all_processes:reported_by_chrome:v8:effective_size_avg/load_social/load_social_twitter
  Change       : 2.44% | 3261942.0 -> 3341638.0

Revision             Result                  N
chromium@491268      3261942 +- 9.38083      14      good
chromium@491283      3264558 +- 67972.7      20      good
chromium@491290      3267568 +- 93080.0      21      good
chromium@491294      3273156 +- 126534       21      good
chromium@491296      3265572 +- 67997.7      14      good
chromium@491297      3321803 +- 190598       21      bad       <--
chromium@491325      3337668 +- 95881.9      14      bad
chromium@491381      3347189 +- 76734.5      6       bad
chromium@491494      3341638 +- 74937.8      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=android-chromium --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=load.social.twitter system_health.memory_mobile

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

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8971703850856762320


For feedback, file a bug with component Speed>Bisection

Given that the regression only occurs on specific sites / cases and the regression is relatively mild, I think that the CL is worth sticking.