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Issue 771111 link

Starred by 1 user
Status: Fixed
Owner:
█ kochi@chromium.org
Last visit > 30 days ago
Closed: Nov 2017
Cc:
█ meade@chromium.org
█ nainar@chromium.org
hayato@chromium.org
Components:
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: 3
Type: Bug

Blocking:
issue 671907



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Measure the usage of /deep/ in static profile

Project Member Reported by kochi@chromium.org, Oct 3 2017 
Background:
https://github.com/w3c/webcomponents/issues/78
(Support `>>>` combinator in static profile)
https://github.com/whatwg/dom/issues/463
(Match querySelector for pseudo elements (::slotted()))

For Shadow DOM V0 we allow '/deep/' and '::shadow' in querySelector()
(aka CSS selector static profile), and if the experimental flag is
enabled, we allow '>>>' for Shadow DOM V1.

It would be worth measuring how popularly '/deep/' and '::shadow'
are used to determine whether we should promote `>>>` or not.

As of this writing, the usage of `>>>` is ~zero.
https://www.chromestatus.com/metrics/feature/timeline/popularity/1691
This is not the proof that it is not useful, but as it is under the
experimental flag.

Comment 1 by kochi@chromium.org, Oct 3 2017 

Other metrics:
CSSDeepCombinator: 0.111248 (/deep/ combinator usage in dynamic profile matching)
https://www.chromestatus.com/metrics/feature/timeline/popularity/471
CSSSelectorPseudoShadow: 0.000883 (::shadow usage in dynamic profile matching)
https://www.chromestatus.com/metrics/feature/timeline/popularity/467CSSDeepCombinatorAndShadow: 0.004326 (/deep/ or ::shadow that actually matches)
https://www.chromestatus.com/metrics/feature/timeline/popularity/1375

Comment 2 by kochi@chromium.org, Oct 5 2017

Blocking: 671907
Status: Started (was: Assigned)

Comment 3 by kochi@chromium.org, Oct 5 2017

Cc: meade@chromium.org nainar@chromium.org hayato@chromium.org
Project Member

Comment 4 by bugdroid1@chromium.org, Oct 5 2017 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9055c1faea785877d31113dc9d2f3d978fe16457

commit 9055c1faea785877d31113dc9d2f3d978fe16457
Author: Takayoshi Kochi <kochi@chromium.org>
Date: Thu Oct 05 14:28:18 2017

Add use counter for /deep/ and ::shadow usage in querySelector()

Bug:  771111 

Change-Id: I7f791cb0c5c32d92adf1e05c6719a37fca871475
Reviewed-on: https://chromium-review.googlesource.com/697190
Commit-Queue: Takayoshi Kochi <kochi@chromium.org>
Reviewed-by: Hayato Ito <hayato@chromium.org>
Reviewed-by: nainar <nainar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#506722}
[modify] https://crrev.com/9055c1faea785877d31113dc9d2f3d978fe16457/third_party/WebKit/Source/core/css/SelectorChecker.cpp
[modify] https://crrev.com/9055c1faea785877d31113dc9d2f3d978fe16457/third_party/WebKit/public/platform/web_feature.mojom
[modify] https://crrev.com/9055c1faea785877d31113dc9d2f3d978fe16457/tools/metrics/histograms/enums.xml

Comment 5 by dtapu...@chromium.org, Nov 10 2017

Components: Blink>DOM>ShadowDOM

Comment 6 by kochi@chromium.org, Nov 22 2017

Status: Fixed (was: Started)
The counters started to appear, will increase when M63 goes stable.
https://www.chromestatus.com/metrics/feature/timeline/popularity/2163 ~0.04%
https://www.chromestatus.com/metrics/feature/timeline/popularity/2164 ~0.08%

Usecounter for '>>>' is still ~0
https://www.chromestatus.com/metrics/feature/timeline/popularity/1691

Cf. current shadow usage:
ElementAttachShadow (V1)
https://www.chromestatus.com/metrics/feature/timeline/popularity/804 ~0.05%
ElementCreateShadowRoot (V0)
https://www.chromestatus.com/metrics/feature/timeline/popularity/456 ~9.5%
►

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