All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=739161

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDgnsyCkQgM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDg3uyJ7AoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDgnpnsrwkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDgnqPl8AsM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDg3o6YiQoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDgnrXn5AgM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDg7uTptAgM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDgnuD2iQsM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDg7qmhlgsM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDg7q2omQkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDgnvb5wgoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDg7vXP1AgM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDg7ruG_AkM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDgnrum7wsM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDgnpzk-QgM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDg3tirpgsM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDgntiwkAoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDg7quC9woM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDgnpfz4goM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDg3tymqQoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDgnrum7wkM


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

chromium-rel-win10
chromium-rel-win7-dual
chromium-rel-win7-gpu-ati
chromium-rel-win7-gpu-intel
chromium-rel-win7-gpu-nvidia
chromium-rel-win8-dual
win-high-dpi

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8974997067689496576

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

Hi yhirano@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 : Yutaka Hirano
  Commit : 3a0905c1392858d49ee03a2081500351d4568320
  Date   : Fri Jun 30 16:09:00 2017
  Subject: Remove PingLoaderImpl

Bisect Details
  Configuration: win_perf_bisect
  Benchmark    : loading.desktop
  Metric       : timeToFirstContentfulPaint_avg/pcv1-warm/money.cnn
  Change       : 48.68% | 259.2105 -> 385.3905

Revision             Result                  N
chromium@483665      259.211 +- 20.8702      6      good
chromium@483693      263.66 +- 4.37838       6      good
chromium@483707      261.869 +- 8.85965      6      good
chromium@483714      281.824 +- 134.263      9      good
chromium@483718      262.607 +- 5.88797      6      good
chromium@483719      265.557 +- 10.627       6      good
chromium@483720      389.009 +- 78.6868      6      bad       <--
chromium@483721      385.39 +- 79.6965       6      bad

To Run This Test
  src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=money.cnn loading.desktop

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

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8974997067689496576


For feedback, file a bug with component Speed>Bisection

All reports are for money.cnn.
I confirmed that PingLoader::LoadImage is used by the story.

https://codereview.chromium.org/2215313003

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7c45454f3655609e883505dc3269b2a6140302a6

commit 7c45454f3655609e883505dc3269b2a6140302a6
Author: yhirano <yhirano@chromium.org>
Date: Thu Jul 13 04:19:56 2017

Set "ping" requests priority as lowest

Requests from PingLoader had the lowest priority, but I changed it
unintentionally. This CL restores the original behavior.

BUG= 739161 

Review-Url: https://codereview.chromium.org/2982523002
Cr-Commit-Position: refs/heads/master@{#486267}

[modify] https://crrev.com/7c45454f3655609e883505dc3269b2a6140302a6/third_party/WebKit/Source/core/loader/PingLoaderTest.cpp
[modify] https://crrev.com/7c45454f3655609e883505dc3269b2a6140302a6/third_party/WebKit/Source/platform/loader/fetch/ResourceFetcher.cpp

Fixed by #6