Bisect at:
https://chromeperf.appspot.com/buildbucket_job_status/9015398959702648512

Forgot to set it to a return code bisect.
Return code bisect here:
https://chromeperf.appspot.com/buildbucket_job_status/9015398605193442112

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


===== SUSPECTED CL(s) =====
Subject : UTF-8 detector for pages missing encoding info
Author  : jinsukkim
Commit description:
  
Experiment crbug.com/518968 shows that about 30% of the pages
missing character encoding information are encoded in UTF-8.
This CL runs a quick one-pass scan against them to check if
they are encoded in UTF-8. It helps get the encoding right
for 30% of the pages without having to turn on full auto-encoding
detection logic which is disabled due to slow performance.

BUG= 583549 
TEST=Layout test: fast/encoding/unlabelled-non-ascii-utf8.html

Review URL: https://codereview.chromium.org/1721373002

Cr-Commit-Position: refs/heads/master@{#387209}
Commit  : 2af3917eb9ca14b263116d664a8257ae69680610
Date    : Thu Apr 14 02:26:47 2016


===== TESTED REVISIONS =====
Revision                Exit Code   Std. Dev.   Num Values  Good?
chromium@387136         0           N/A         2           good
chromium@387180         0           N/A         2           good
chromium@387202         0           N/A         2           good
chromium@387208         0           N/A         2           good
chromium@387209         1           N/A         2           bad         <-
chromium@387210         1           N/A         2           bad
chromium@387211         1           N/A         2           bad
chromium@387213         1           N/A         2           bad
chromium@387224         1           N/A         2           bad

Bisect job ran on: linux_perf_bisect
Bug ID: 603558

Test Command: src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --also-run-disabled-tests jetstream
Test Metric: 3d-cube/3d-cube
Relative Change: Zero to non-zero
Score: 0.0

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/linux_perf_bisect/builds/6419
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9015398605193442112


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=603558

| 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!

Jetstream passed on first run with revert.

https://build.chromium.org/p/chromium.perf/builders/Linux%20Perf%20%283%29/builds/15964

Awesome. Junsukkim: please also reference this bug in your relanding.

 Issue 603560  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/57139d64c5b98142ca9305792f39ae23a4950375

commit 57139d64c5b98142ca9305792f39ae23a4950375
Author: jinsukkim <jinsukkim@chromium.org>
Date: Thu Apr 21 22:33:24 2016

Reland "UTF-8 detector for pages missing encoding info"

TextResourceDecoder is designed (or used) in such a way that the text
encoding of a document gets resolved from the first chunk (as big as
4096 bytes) of the text received from network - by BOM, meta tag, or
auto encoding detection (if enabled).

The newly introduced UTF-8 encoding detector crrev.com/1721373002 was
reverted ( crbug.com/603558 ) because it attempted to work in a bit
different way - it examined all the subsequent chunks as well in search
of non-ASCII-UTF-8-encoded char sequence. This means it is possible for
TextResourceDecoder to start with a codec for, say, windows-1252, and
then later switch to one for UTF-8. Theoretically this should still work
but doesn't in practice (maybe hasn't been used/tested in that
way). This is what happened with failed perf tests - one of the js files
was big (13K), of pure ASCII except one tiny char sequence \xc2\xa7
almost at the end.

The CL was updated so the UTF-8 encoding detection also works against
the first chunk only like other methods, to avoid potential codec
switching in the middle.

BUG= 583549 , 603558 

Review URL: https://codereview.chromium.org/1890103002

Cr-Commit-Position: refs/heads/master@{#388927}

[add] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/LayoutTests/fast/encoding/unlabelled-non-ascii-utf8-expected.html
[add] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/LayoutTests/fast/encoding/unlabelled-non-ascii-utf8.html
[modify] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/Source/core/core.gypi
[modify] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/Source/core/html/parser/TextResourceDecoder.cpp
[modify] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/Source/core/html/parser/TextResourceDecoder.h
[add] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/Source/core/html/parser/TextResourceDecoderTest.cpp
[modify] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp
[modify] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/Source/platform/text/TextEncodingDetector.cpp
[modify] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/Source/platform/text/TextEncodingDetector.h
[modify] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/Source/wtf/text/UTF8.cpp
[modify] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/Source/wtf/text/UTF8.h
[add] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/Source/wtf/text/UTF8Test.cpp
[modify] https://crrev.com/57139d64c5b98142ca9305792f39ae23a4950375/third_party/WebKit/Source/wtf/wtf.gypi