All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=873883

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=eebe4bc1057e1a7c25ef546f8e8d11ed82b846fbd181935af7de750cf77155f8


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

Android Nexus6 WebView Perf

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/14a2aa5c640000

📍 Found a significant difference after 1 commit.
https://pinpoint-dot-chromeperf.appspot.com/job/14a2aa5c640000

[PE] Stop dirtying compositing inputs on any layout for the root PaintLayer. by chrishtr@chromium.org
https://chromium.googlesource.com/chromium/src/+/46520ae13478333fe882e79041b667e5a3112796
0.05089 → 0.1597 (+0.1088)

Understanding performance regressions:
  http://g.co/ChromePerformanceRegressions

Issue 873896 has been merged into this issue.

Issue 873900 has been merged into this issue.

Also:

https://chromeperf.appspot.com/group_report?bug_id=873896
https://chromeperf.appspot.com/group_report?bug_id=873900
https://chromeperf.appspot.com/group_report?bug_id=874891
https://chromeperf.appspot.com/group_report?bug_id=874893
https://chromeperf.appspot.com/group_report?bug_id=875326
https://chromeperf.appspot.com/group_report?bug_id=875330
https://chromeperf.appspot.com/group_report?bug_id=875416

 Issue 876018  has been merged into this issue.

I think my patch over-invalidated compositing inputs, causing too much
CPU work. In particular it started doing so after overflow scroll, not just
layout.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1fde0aa321a73ca57f90ce1673eab128f35540e9

commit 1fde0aa321a73ca57f90ce1673eab128f35540e9
Author: Chris Harrelson <chrishtr@chromium.org>
Date: Wed Aug 22 17:24:09 2018

[PE] Don't invalidate compositing inputs on scroll.

An earlier patch (http://crrev.com/582337) regressed this.

Bug:  873883 

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ie5fe1149ac1da2df7c1a59864339f5b5982527ff
Reviewed-on: https://chromium-review.googlesource.com/1183596
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: vmpstr <vmpstr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585128}
[modify] https://crrev.com/1fde0aa321a73ca57f90ce1673eab128f35540e9/third_party/blink/renderer/core/paint/paint_layer.cc
[modify] https://crrev.com/1fde0aa321a73ca57f90ce1673eab128f35540e9/third_party/blink/renderer/core/paint/paint_layer.h

Still a problem:

https://chromeperf.appspot.com/group_report?bug_id=873883
https://chromeperf.appspot.com/group_report?bug_id=875326
https://chromeperf.appspot.com/group_report?bug_id=875330
https://chromeperf.appspot.com/group_report?bug_id=875416

some of:

https://chromeperf.appspot.com/group_report?bug_id=873900
https://chromeperf.appspot.com/group_report?bug_id=873896

 Issue 875911  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/87237f87304e8ee3c9857c9499b4dd4d4a52ca2a

commit 87237f87304e8ee3c9857c9499b4dd4d4a52ca2a
Author: Chris Harrelson <chrishtr@chromium.org>
Date: Mon Aug 27 18:40:36 2018

Pass along |dirty_compositing_if_needed| recursively.

This was a mistake in commit 1fde0aa321a73ca57f90ce1673eab128f35540e9.

Bug:  873883 

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ia48ad8ddc5d63225ccca1a2b8d6f26920de605a5
Reviewed-on: https://chromium-review.googlesource.com/1190923
Reviewed-by: vmpstr <vmpstr@chromium.org>
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586332}
[modify] https://crrev.com/87237f87304e8ee3c9857c9499b4dd4d4a52ca2a/third_party/blink/renderer/core/paint/paint_layer.cc

 Issue 876081  has been merged into this issue.

 Issue 876079  has been merged into this issue.

https://chromeperf.appspot.com/group_report?bug_id=875416

has now recovered. Waiting for more bots to catch up.

Going to assume fixed. Some of these bots are stuck/taking forever to update.