All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=621155

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICggs3_qgoM


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

android-nexus7v2

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


=== Bisection aborted ===
The bisect was aborted because The metric values for the initial "good" and "bad" revisions do not represent a clear regression.
Please contact the the team (see below) if you believe this is in error.

=== Warnings ===
The following warnings were raised by the bisect job:

 * Bisect failed to reproduce the regression with enough confidence.

===== TESTED REVISIONS =====
Revision         Mean     Std Dev  N   Good?
chromium@399669  76.5498  4.76902  12  good
chromium@399678  78.5204  1.18311  8   bad

Bisect job ran on: android_nexus7_perf_bisect
Bug ID: 621155

Test Command: src/tools/perf/run_benchmark -v --browser=android-chromium --output-format=chartjson --upload-results --also-run-disabled-tests blink_perf.parser
Test Metric: query-selector-last/query-selector-last
Relative Change: 4.83%
Score: 0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/android_nexus7_perf_bisect/builds/3016
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9009581989899447696


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5903820173869056

| 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!

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


=== Bisection aborted ===
The bisect was aborted because The metric values for the initial "good" and "bad" revisions do not represent a clear regression.
Please contact the the team (see below) if you believe this is in error.

=== Warnings ===
The following warnings were raised by the bisect job:

 * Bisect failed to reproduce the regression with enough confidence.

===== TESTED REVISIONS =====
Revision         Mean     Std Dev  N   Good?
chromium@399669  81.5881  3.73976  12  good
chromium@399678  81.1516  4.3244   8   bad

Bisect job ran on: android_nexus7_perf_bisect
Bug ID: 621155

Test Command: src/tools/perf/run_benchmark -v --browser=android-chromium --output-format=chartjson --upload-results --also-run-disabled-tests blink_perf.parser
Test Metric: query-selector-last/query-selector-last
Relative Change: 0.91%
Score: 0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/android_nexus7_perf_bisect/builds/3044
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9008138087808825808


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5805701813764096

| 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!

Moving this nonessential bug to the next milestone.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

YAB: https://chromeperf.appspot.com/buildbucket_job_status/9007409040846598160

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9006406766868175088

Trying a wider bisect.

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

Hi tzik@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 : Introduce base::IsWeakReceiver for base::Bind to support external weak pointers
Author  : tzik
Commit description:
  
base::IsWeakReceiver is an injection point for external libraries to
configure a receiver to behave as a weak pointer. Namely, WTF::WeakPtr,
WTF::WeakPersistent and WTF::CrossThreadWeakPersistent in Blink will be
specialize base::IsWeakReceiver, and the callback will be cancelled on
null instances of them.

Review-Url: https://codereview.chromium.org/2048023004
Cr-Commit-Position: refs/heads/master@{#399689}
Commit  : 1ae80b2655df4f23b87776625de2ae8eb0e03df2
Date    : Tue Jun 14 13:21:04 2016


===== TESTED REVISIONS =====
Revision         Mean     Std Dev   N  Good?
chromium@399669  79.3234  1.53616   5  good
chromium@399683  79.41    1.30433   8  good
chromium@399687  77.5605  5.12939   8  good
chromium@399688  75.4576  5.25906   5  good
chromium@399689  66.9232  1.5013    8  bad    <--
chromium@399690  65.3447  2.45234   8  bad
chromium@399697  66.5615  0.677081  5  bad
chromium@399725  66.8714  0.699173  5  bad
chromium@399780  65.5333  1.28732   5  bad

Bisect job ran on: android_nexus7_perf_bisect
Bug ID: 621155

Test Command: src/tools/perf/run_benchmark -v --browser=android-chromium --output-format=chartjson --upload-results --also-run-disabled-tests blink_perf.parser
Test Metric: query-selector-last/query-selector-last
Relative Change: 17.38%
Score: 99.9

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/android_nexus7_perf_bisect/builds/3090
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9006406766868175088


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5781528278204416

| 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!

My change was likely not affect the performance of these test.
The deviation of the metric was high at that time, and became low around 399766-399829, so something happened around that range.

Sorry about that, tzik! Agreed with your comment, the test seemed to be bimodal between the high and low values and now always reports the low value. Assigning to blink_perf.parser owner yukishiino, since the test was previously bimodal it's hard to bisect correctly. This only happens on one device type (nexus 7). Anything that can be done here, or should we WontFix?

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9005516282862648640

Lets try another bisect, but it's possible this will end ups as wontfix.

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


=== Bisection aborted ===
The bisect was aborted because The metric values for the initial "good" and "bad" revisions do not represent a clear regression.
Please contact the the team (see below) if you believe this is in error.

=== Warnings ===
The following warnings were raised by the bisect job:

 * Bisect failed to reproduce the regression with enough confidence.

===== TESTED REVISIONS =====
Revision         Mean     Std Dev   N   Good?
chromium@399600  67.2844  1.03508   12  good
chromium@399700  66.6886  0.902652  8   bad

Bisect job ran on: android_nexus7_perf_bisect
Bug ID: 621155

Test Command: src/tools/perf/run_benchmark -v --browser=android-chromium --output-format=chartjson --upload-results --also-run-disabled-tests blink_perf.parser
Test Metric: query-selector-last/query-selector-last
Relative Change: 0.74%
Score: 0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/android_nexus7_perf_bisect/builds/3130
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9005516282862648640


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5830792651997184

| 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!

Because it already recovered (and regressed again), close this specific issue as WontFix.