All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=759490

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=d7233f2eaecc59378f1f8c8986cad35c14d889170cb0369899941ed89a26bd78


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

android-nexus5

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8970027348207428464

=== Auto-CCing suspected CL author jeffreyhe@google.com ===

Hi jeffreyhe@google.com, 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 : Jeffrey He
  Commit : a9a085dd2b2d0c3f838d6341571099baaeb0c99b
  Date   : Tue Aug 08 15:05:01 2017
  Subject: Remove worker detachment.

Bisect Details
  Configuration: android_nexus5_perf_bisect
  Benchmark    : v8.runtimestats.browsing_mobile
  Metric       : JavaScript:duration_avg/browse_media/browse_media_youtube
  Change       : 1.10% | 4494.11507143 -> 4435.52914286

Revision             Result                  N
chromium@492617      4494.12 +- 120.175      14      good
chromium@492621      4505.63 +- 83.4047      14      good
chromium@492622      4456.74 +- 92.9991      9       bad       <--
chromium@492623      4465.02 +- 159.523      21      bad
chromium@492630      4452.23 +- 203.434      21      bad
chromium@492637      4440.7 +- 148.079       14      bad
chromium@492657      4445.43 +- 69.8737      6       bad
chromium@492698      4453.59 +- 167.221      21      bad
chromium@492778      4457.52 +- 192.595      21      bad
chromium@492940      4435.53 +- 109.167      14      bad

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=browse.media.youtube v8.runtimestats.browsing_mobile

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

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8970027348207428464


For feedback, file a bug with component Speed>Bisection

The assigned owner "jeffreyhe@google.com" is not able to receive e-mails, please re-triage.

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

Re-assigning to a CL reviewer for further triage.

Is there an actual regression here? If anything based off of the results listed in the bisect, things got slightly faster after the CL. Am I reading this correctly?

Oh, you are right, this doesn't make any sense.