All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=606267

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgpLHUogoM,agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgpLaDuQoM


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

chromium-rel-mac-retina
chromium-rel-mac11

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

Hi jinsukkim@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 : Reland "UTF-8 detector for pages missing encoding info"
Author  : jinsukkim
Commit description:
  
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}
Commit  : 57139d64c5b98142ca9305792f39ae23a4950375
Date    : Thu Apr 21 22:35:47 2016


===== TESTED REVISIONS =====
Revision                Mean Value  Std. Dev.   Num Values  Good?
chromium@388919         59.279      0.94382     5           good
chromium@388924         59.6432     0.623485    5           good
chromium@388926         59.9152     0.875503    5           good
chromium@388927         66.0578     1.444041    5           bad         <-
chromium@388928         64.5256     0.874496    5           bad
chromium@388937         65.173      0.684897    5           bad

Bisect job ran on: mac_10_11_perf_bisect
Bug ID: 606267

Test Command: src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --also-run-disabled-tests blink_perf.svg
Test Metric: WorldIso/WorldIso
Relative Change: 9.94%
Score: 99.9

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/mac_10_11_perf_bisect/builds/601
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9014426787236392816


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=606267

| 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!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/472f4e7c9b1ce63e453be41e938520dec30af46b

commit 472f4e7c9b1ce63e453be41e938520dec30af46b
Author: jinsukkim <jinsukkim@chromium.org>
Date: Tue Apr 26 22:37:08 2016

Add XML header to test SVG file

WorldIso.svg is the only file in the SVG performance test suite
that's missing the xml header. This triggered auto-encoding detector or
UTF-8 encoding detector and caused extra amount of time in the result,
which is not the purpose of the test suite. Added a header used
in other svg (Worldcup.svg). This fixes the regression reported
in blink_perf.svg.

BUG= 606267 

Review URL: https://codereview.chromium.org/1922843002

Cr-Commit-Position: refs/heads/master@{#389923}

[modify] https://crrev.com/472f4e7c9b1ce63e453be41e938520dec30af46b/third_party/WebKit/PerformanceTests/SVG/resources/WorldIso.svg