Wangsong Jin (Gerrit)

unread,

Jan 12, 2026, 5:20:16 PMJan 12

to Claire Chambers, Olga Gerchikov, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, Chromium LUCI CQ, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Attention needed from Claire Chambers and Olga Gerchikov

Wangsong Jin added 3 comments

Patchset-level comments

File-level comment, Patchset 1 (Latest):

Wangsong Jin . unresolved

Do we have test coverage for will-change:clip-path without backdrop filter won't create a backdrop root?

File third_party/blink/renderer/core/paint/paint_property_tree_builder.cc

Line 1739, Patchset 1 (Latest): if (object_.HasLayer()) {

Wangsong Jin . unresolved

Do we still need a feature gate here?

Line 1754, Patchset 1 (Latest):

  if (RuntimeEnabledFeatures::
          BackdropRootForClipPathWithBackdropFilterEnabled() &&
      properties_ && properties_->ClipPathClip() && object_.HasLayer()) {
  }

Wangsong Jin . unresolved

This if block is now empty.

Open in Gerrit

Related details

Attention is currently required from:

Claire Chambers
Olga Gerchikov

Submit Requirements:

Code-Coverage
Code-Owners
Code-Review
No-Unresolved-Comments
Review-Enforcement

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

satisfied_requirement

unsatisfied_requirement

open

diffy

Claire Chambers (Gerrit)

unread,

Jan 13, 2026, 1:03:46 PMJan 13

to Olga Gerchikov, Wangsong Jin, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, Chromium LUCI CQ, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Attention needed from Olga Gerchikov and Wangsong Jin

Claire Chambers added 1 comment

Patchset-level comments

File-level comment, Patchset 1 (Latest):

Wangsong Jin . resolved

Do we have test coverage for will-change:clip-path without backdrop filter won't create a backdrop root?

Claire Chambers

This is impossible to check with a web test as the only way to visually determine whether a backdrop root exists is by putting a backdrop filter over it. Anything else would be a bug.

Open in Gerrit

Related details

Attention is currently required from:

Olga Gerchikov
Wangsong Jin

Submit Requirements:

Code-Coverage
Code-Owners
Code-Review
No-Unresolved-Comments
Review-Enforcement

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

satisfied_requirement

unsatisfied_requirement

open

diffy

Wangsong Jin (Gerrit)

unread,

Jan 13, 2026, 5:52:03 PMJan 13

to Claire Chambers, Olga Gerchikov, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, Chromium LUCI CQ, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Attention needed from Claire Chambers and Olga Gerchikov

Wangsong Jin added 2 comments

File third_party/blink/renderer/core/paint/paint_property_tree_builder.cc

Line 1734, Patchset 1 (Latest):

Wangsong Jin . unresolved

Nit: Empty line.

Line 1739, Patchset 1 (Latest): if (object_.HasLayer()) {

Wangsong Jin . resolved

Do we still need a feature gate here?

Wangsong Jin

Just a reminder: if `BackdropRootForClipPathWithBackdropFilterEnabled` is no longer needed, please remove it from runtime_enabled_features.json5.

Open in Gerrit

Related details

Attention is currently required from:

Claire Chambers
Olga Gerchikov

Submit Requirements:

Code-Coverage
Code-Owners
Code-Review
No-Unresolved-Comments
Review-Enforcement

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

satisfied_requirement

unsatisfied_requirement

open

diffy

Claire Chambers (Gerrit)

unread,

Jan 15, 2026, 1:23:30 AMJan 15

to Olga Gerchikov, Wangsong Jin, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, Chromium LUCI CQ, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Attention needed from Olga Gerchikov and Wangsong Jin

Claire Chambers added 2 comments

File third_party/blink/renderer/core/paint/paint_property_tree_builder.cc

Line 1734, Patchset 1:

Wangsong Jin . resolved

Nit: Empty line.

Claire Chambers

Acknowledged

Line 1754, Patchset 1: if (RuntimeEnabledFeatures::


          BackdropRootForClipPathWithBackdropFilterEnabled() &&
      properties_ && properties_->ClipPathClip() && object_.HasLayer()) {
  }

Wangsong Jin . resolved

This if block is now empty.

Claire Chambers

Done

Open in Gerrit

Related details

Attention is currently required from:

Olga Gerchikov
Wangsong Jin

Submit Requirements:

Code-Coverage
Code-Owners
Code-Review

Review-Enforcement

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

satisfied_requirement

unsatisfied_requirement

open

diffy

Wangsong Jin (Gerrit)

unread,

Jan 15, 2026, 12:35:07 PMJan 15

to Claire Chambers, Olga Gerchikov, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, Chromium LUCI CQ, jmedle...@chromium.org, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Attention needed from Claire Chambers and Olga Gerchikov

Wangsong Jin added 1 comment

Patchset-level comments

File-level comment, Patchset 2 (Latest):

Wangsong Jin . resolved

LGTM

Open in Gerrit

Related details

Attention is currently required from:

Claire Chambers
Olga Gerchikov

Submit Requirements:

Code-Coverage
Code-Owners
Code-Review
Review-Enforcement

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

satisfied_requirement

unsatisfied_requirement

open

diffy

Philip Rogers (Gerrit)

unread,

Feb 2, 2026, 9:10:11 PM (11 days ago) Feb 2

to Claire Chambers, Olga Gerchikov, Wangsong Jin, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, Chromium LUCI CQ, jmedle...@chromium.org, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Attention needed from Claire Chambers and Olga Gerchikov

Philip Rogers added 2 comments

File third_party/blink/renderer/platform/graphics/compositing_reasons.h

Line 155, Patchset 3 (Latest): kDirectReasonsForEffectProperty =

Philip Rogers . unresolved

Shouldn't we have kWillChangeMask and kWillChangeMaskImage here as well? Maybe I misunderstand, but don't we want to set things up so that a mask can change without re-drawing everything, even if there isn't a backdrop filter?

File third_party/blink/web_tests/external/wpt/css/filter-effects/backdrop-filter-backdrop-root-mask.html

Line 4, Patchset 3 (Latest):<link rel="author" href="mailto:mas...@chromium.org">

Philip Rogers . unresolved

clcha...@microsoft.com?

Open in Gerrit

Related details

Attention is currently required from:

Claire Chambers
Olga Gerchikov

Submit Requirements:

Code-Coverage
Code-Owners
Code-Review

No-Unresolved-Comments

Review-Enforcement

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

satisfied_requirement

unsatisfied_requirement

open

diffy

Claire Chambers (Gerrit)

unread,

Feb 3, 2026, 2:44:52 PM (10 days ago) Feb 3

to Philip Rogers, Olga Gerchikov, Wangsong Jin, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, Chromium LUCI CQ, jmedle...@chromium.org, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Attention needed from Olga Gerchikov and Philip Rogers

Claire Chambers added 2 comments

File third_party/blink/renderer/platform/graphics/compositing_reasons.h

Line 155, Patchset 3: kDirectReasonsForEffectProperty =

Philip Rogers . unresolved

Shouldn't we have kWillChangeMask and kWillChangeMaskImage here as well? Maybe I misunderstand, but don't we want to set things up so that a mask can change without re-drawing everything, even if there isn't a backdrop filter?

Claire Chambers

Masks don't normally create an effect node, and that would be a pretty big perf change. The point of this CL is to only create effect nodes for them when a backdrop filter is/will be present, to meet spec while minimizing perf impact.

File third_party/blink/web_tests/external/wpt/css/filter-effects/backdrop-filter-backdrop-root-mask.html

Line 4, Patchset 3:<link rel="author" href="mailto:mas...@chromium.org">

Philip Rogers . resolved

clcha...@microsoft.com?

Claire Chambers

Ack! Lesson in why you should never blindly copy-paste. Fixed.

Open in Gerrit

Related details

Attention is currently required from:

Olga Gerchikov
Philip Rogers

Submit Requirements:

Code-Coverage
Code-Owners
Code-Review
No-Unresolved-Comments
Review-Enforcement

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

satisfied_requirement

unsatisfied_requirement

open

diffy

Philip Rogers (Gerrit)

unread,

Feb 3, 2026, 4:34:03 PM (10 days ago) Feb 3

to Claire Chambers, Olga Gerchikov, Wangsong Jin, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, Chromium LUCI CQ, jmedle...@chromium.org, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Attention needed from Claire Chambers and Olga Gerchikov

Philip Rogers voted and added 2 comments

Votes added by Philip Rogers

Code-Review

+1

2 comments

Patchset-level comments

File-level comment, Patchset 4 (Latest):

Philip Rogers . resolved

LGTM

File third_party/blink/renderer/platform/graphics/compositing_reasons.h

Line 155, Patchset 3: kDirectReasonsForEffectProperty =

Philip Rogers . resolved

Shouldn't we have kWillChangeMask and kWillChangeMaskImage here as well? Maybe I misunderstand, but don't we want to set things up so that a mask can change without re-drawing everything, even if there isn't a backdrop filter?

Claire Chambers

Masks don't normally create an effect node, and that would be a pretty big perf change. The point of this CL is to only create effect nodes for them when a backdrop filter is/will be present, to meet spec while minimizing perf impact.

Philip Rogers

Acknowledged

Open in Gerrit

Related details

Attention is currently required from:

Claire Chambers
Olga Gerchikov

Submit Requirements:

Code-Coverage
Code-Owners
Code-Review
Review-Enforcement

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

satisfied_requirement

open

diffy

Blink W3C Test Autoroller (Gerrit)

unread,

Feb 3, 2026, 4:49:16 PM (10 days ago) Feb 3

to Claire Chambers, Philip Rogers, Olga Gerchikov, Wangsong Jin, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, Chromium LUCI CQ, jmedle...@chromium.org, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Attention needed from Claire Chambers and Olga Gerchikov

Message from Blink W3C Test Autoroller

Exportable changes to web-platform-tests were detected in this CL and a pull request in the upstream repo has been made: https://github.com/web-platform-tests/wpt/pull/57550.

When this CL lands, the bot will automatically merge the PR on GitHub if the required GitHub checks pass; otherwise, ecosystem-infra@ team will triage the failures and may contact you.

WPT Export docs:
https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md#Automatic-export-process

Open in Gerrit

Related details

Attention is currently required from:

Claire Chambers
Olga Gerchikov

Submit Requirements:

Code-Coverage
Code-Owners
Code-Review
Review-Enforcement

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

satisfied_requirement

open

diffy

Claire Chambers (Gerrit)

unread,

Feb 5, 2026, 3:00:41 AM (9 days ago) Feb 5

to Blink W3C Test Autoroller, Philip Rogers, Olga Gerchikov, Wangsong Jin, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, Chromium LUCI CQ, jmedle...@chromium.org, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Attention needed from Olga Gerchikov

Claire Chambers voted Commit-Queue+2

Commit-Queue

+2

Open in Gerrit

Related details

Attention is currently required from:

Olga Gerchikov

Submit Requirements:

Code-Coverage
Code-Owners
Code-Review
Review-Enforcement

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

satisfied_requirement

open

diffy

Chromium LUCI CQ (Gerrit)

unread,

Feb 5, 2026, 3:24:29 AM (9 days ago) Feb 5

to Claire Chambers, Blink W3C Test Autoroller, Philip Rogers, Olga Gerchikov, Wangsong Jin, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, jmedle...@chromium.org, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Chromium LUCI CQ submitted the change with unreviewed changes

Unreviewed changes

4 is the latest approved patch-set.
The change was submitted with unreviewed changes in the following files:

```
The name of the file: third_party/blink/renderer/platform/graphics/compositing_reasons.h
Insertions: 1, Deletions: 1.

The diff is too large to show. Please review the diff.
```

Change information

Commit message:

Add kAuxiliaryReasonsForBackdropRoot, fix bugs for backdrop root

This change fixes two bugs - that mask images did not create backdrop
roots even though the spec demands it - and, that will-change: clip-path
created a backdrop root even when a child backdrop filter was not
present, making will-change: clip-path an anti-optimization for clip-
path.

A test is added to ensure the behavior for masks is correct.

Bug: 474391730

Change-Id: I052080412f3d77d022fe8caa72421d0a3c3091ac

Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7425346

Reviewed-by: Philip Rogers <p...@chromium.org>

Commit-Queue: Claire Chambers <clcha...@microsoft.com>

Cr-Commit-Position: refs/heads/main@{#1579930}

Files:

M third_party/blink/renderer/core/paint/compositing/compositing_reason_finder.cc
M third_party/blink/renderer/core/paint/paint_property_tree_builder.cc
M third_party/blink/renderer/core/style/computed_style.h
M third_party/blink/renderer/platform/graphics/compositing_reasons.cc
M third_party/blink/renderer/platform/graphics/compositing_reasons.h
M third_party/blink/renderer/platform/runtime_enabled_features.json5
A third_party/blink/web_tests/external/wpt/css/filter-effects/backdrop-filter-backdrop-root-mask-ref.html
A third_party/blink/web_tests/external/wpt/css/filter-effects/backdrop-filter-backdrop-root-mask.html

Change size: M

Delta: 8 files changed, 95 insertions(+), 15 deletions(-)

Branch: refs/heads/main

Submit Requirements:

Code-Review: +1 by Philip Rogers

Open in Gerrit

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

open

diffy

satisfied_requirement

Blink W3C Test Autoroller (Gerrit)

unread,

Feb 5, 2026, 4:04:14 AM (9 days ago) Feb 5

to Chromium LUCI CQ, Claire Chambers, Philip Rogers, Olga Gerchikov, Wangsong Jin, AyeAye, chromium...@chromium.org, Dirk Schulze, Stephen Chenney, jmedle...@chromium.org, blink-rev...@chromium.org, blink-reviews-p...@chromium.org, blink-rev...@chromium.org, blink-revie...@chromium.org, blink-...@chromium.org, drott+bl...@chromium.org, fmalit...@chromium.org, fserb...@chromium.org, kinuko...@chromium.org

Message from Blink W3C Test Autoroller

The WPT PR for this CL has been merged upstream! https://github.com/web-platform-tests/wpt/pull/57550

Open in Gerrit

Related details

Attention set is empty

Submit Requirements:

Code-Coverage
Code-Owners
Code-Review
Review-Enforcement

Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings.

Gerrit

satisfied_requirement

open

diffy

Reply all

Reply to author

Forward

Add kAuxiliaryReasonsForBackdropRoot, fix bugs for backdrop root [chromium/src : main]

Wangsong Jin (Gerrit)

Wangsong Jin added 3 comments

Related details

Claire Chambers (Gerrit)

Claire Chambers added 1 comment

Related details

Wangsong Jin (Gerrit)

Wangsong Jin added 2 comments

Related details

Claire Chambers (Gerrit)

Claire Chambers added 2 comments

Related details

Wangsong Jin (Gerrit)

Wangsong Jin added 1 comment

Related details

Philip Rogers (Gerrit)

Philip Rogers added 2 comments

Related details

Claire Chambers (Gerrit)

Claire Chambers added 2 comments

Related details

Philip Rogers (Gerrit)

Philip Rogers voted and added 2 comments

Votes added by Philip Rogers

2 comments

Related details

Blink W3C Test Autoroller (Gerrit)

Message from Blink W3C Test Autoroller

Related details

Claire Chambers (Gerrit)

Claire Chambers voted Commit-Queue+2

Related details

Chromium LUCI CQ (Gerrit)

Chromium LUCI CQ submitted the change with unreviewed changes

Unreviewed changes

Change information

Blink W3C Test Autoroller (Gerrit)

Message from Blink W3C Test Autoroller

Related details