All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=659059

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg3bLPrwoM


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

android-nexus9

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8997836127371635120

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

Hi chrishtr@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 : Don't apply clips to children of composited-scrolling elements for overlap testing.
Author  : chrishtr
Commit description:
  
However, only compare these unclipped rects with other unclipped rects. This
prevents excessive layer explosion outside of the composited-scrolling layer.

This requires storing unclipped absolute rects for every PaintLayer.

BUG= 652448 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://chromiumcodereview.appspot.com/2425873005
Cr-Commit-Position: refs/heads/master@{#426664}
Commit  : 0a78cbe13de10c5a1c951d753fd13d01c8b3488e
Date    : Fri Oct 21 00:56:33 2016


===== TESTED REVISIONS =====
Revision         Mean      Std Dev     N  Good?
chromium@426621  0.243763  0.00282501  5  good
chromium@426659  0.252378  0.0172049   8  good
chromium@426662  0.257922  0.00175157  5  good
chromium@426663  0.25841   0.0037496   5  good
chromium@426664  0.21277   0.00499877  5  bad    <--
chromium@426669  0.224408  0.0173635   8  bad
chromium@426678  0.21597   0.00407663  8  bad
chromium@426697  0.218691  0.0041614   5  bad

Bisect job ran on: android_nexus9_perf_bisect
Bug ID: 659059

Test Command: src/tools/perf/run_benchmark -v --browser=android-chromium --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests blink_perf.events
Test Metric: hit-test-lots-of-layers/hit-test-lots-of-layers
Relative Change: 10.29%
Score: 99.9

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/android_nexus9_perf_bisect/builds/2210
Job details: https://chromeperf.appspot.com/buildbucket_job_status/8997836127371635120


Not what you expected? We'll investigate and get back to you!
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5847069082779648

| 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/+/8af9d0bee7cdbd2db09562939b7d33696d9a7447

commit 8af9d0bee7cdbd2db09562939b7d33696d9a7447
Author: chrishtr <chrishtr@chromium.org>
Date: Tue Nov 08 03:48:19 2016

Move all ancestor-dependent properties out of PaintLayer and into an aux. struct.

This makes PaintLayer smaller, which improves performance of code, such as hit
testing, that does not need to use these ancestor-dependent compositing properties.

This patch makes hit testing on paint layers >= 15% faster. In particular, it makes
the Events/hit-test-lots-of-layers.html performance test ~15% faster. It had
recently regressed when I added an IntRect.)

BUG= 659059 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2479403002
Cr-Commit-Position: refs/heads/master@{#430509}

[modify] https://crrev.com/8af9d0bee7cdbd2db09562939b7d33696d9a7447/third_party/WebKit/Source/core/layout/compositing/CompositingInputsUpdater.cpp
[modify] https://crrev.com/8af9d0bee7cdbd2db09562939b7d33696d9a7447/third_party/WebKit/Source/core/paint/PaintLayer.cpp
[modify] https://crrev.com/8af9d0bee7cdbd2db09562939b7d33696d9a7447/third_party/WebKit/Source/core/paint/PaintLayer.h