All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=638025

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgjoe0oAkM


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

chromium-rel-mac-hdd

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9004218920873327776

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

Hi abakalov@chromium.org, the bisect results pointed to your CL below as possibly
causing a regression. Please have a look at this info and see whether
your CL be related.


===== BISECT JOB RESULTS =====
Status: completed


===== SUSPECTED CL(s) =====
Subject : Switching from the old (CLD2) to the new (CLD3) language detector.
Author  : abakalov
Commit description:
  
Note:
I ran tools/linux/dump-static-initializers.py on CLD3. It did not find any static initializers.

BUG=624904

Review-Url: https://codereview.chromium.org/2244683002
Cr-Commit-Position: refs/heads/master@{#411677}
Commit  : 5b70d355c174c026f936cb5ef795b4d66c1cc4f5
Date    : Fri Aug 12 16:50:05 2016


===== TESTED REVISIONS =====
Revision         Mean     Std Dev   N  Good?
chromium@411654  15.8278  0.431101  5  good
chromium@411670  15.5924  0.418357  5  good
chromium@411674  15.9272  0.819067  5  good
chromium@411676  15.7644  0.483416  5  good
chromium@411677  19.2866  1.65838   5  bad    <--
chromium@411678  19.5484  1.50587   5  bad
chromium@411685  18.7552  1.61314   5  bad

Bisect job ran on: mac_hdd_perf_bisect
Bug ID: 638025

Test Command: src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --also-run-disabled-tests blink_perf.shadow_dom
Test Metric: MultipleInsertionPoints/MultipleInsertionPoints
Relative Change: 18.50%
Score: 99.0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/mac_hdd_perf_bisect/builds/735
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9004218920873327776


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5855670125985792

| O O | Visit http://www.chromium.org/developers/speed-infra/perf-bug-faq
|  X  | for more information addressing perf regression bugs. For feedback,
| / \ | file a bug with component Tests>AutoBisect.  Thank you!

Based on a discussion with hayato@ (the TL for the Web Components project), it's unlikely that our CL (which is about replacing the Chrome language identification model) is responsible for the regression.

A snippet from what Hayato said:
- They all are micro benchmarks to detect an unintentional regression caused by touching code related with Shadow DOM. e.g. the cost of distribution and style recalculation.
- Given that it only hits MacOS, and the regression was not reflected on other performance tests, it is unlikely that the CL is responsible for that.

 Issue 638004  has been merged into this issue.