commit 2d164fe4a0d3a664af29fbae8edf713168c53974
author Koji Ishii <kojii@chromium.org> Thu Apr 17 01:49:00 2025
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Apr 17 01:49:00 2025
tree e9059d047bb7107e0995969100c1ffc05c1e9a06
parent fc3517f34c70da3d38ebd396e8e6f22217c864c7

Revert "[break-iterator] Keep an instance of grapheme cluster iterator"

This reverts commit 6aa052acda7a5591d6bdf3d8de779942ba8f1226.

Reason for revert: crbug.com/410930625

The `NonSharedCharacterBreakIterator`, despite its name,
shares its internal ICU break iterator, and thus should not be
created more than one instance per thread.

Original change's description:
> [break-iterator] Keep an instance of grapheme cluster iterator
>
> Constructing `NonSharedCharacterBreakIterator` isn't too
> expensive, it doesn't clone the input string, etc.
>
> But it turned out that there are some cases where the
> `LazyLineBreakIterator::NextBreakablePositionBreakCharacter`
> is very hot, such as computing min-size of 16-bits text with
> `word-break: break-word`. In such cases, setting up `utext`,
> which involves setting up several function pointers in a
> vtable-like data structure, is not trivial.
>
> For example, in the `Editor-CodeMirror` of the Speedometer3,
> the `NonSharedCharacterBreakIterator` constructor consumes
> 0.18%. Keeping an instance in the `LazyLineBreakIterator`
> reduces it to 0.06%.
>
> This difference isn't observable in pinpoint. The score vary
> from +0.1% to -0.2%; slightly positive if we take an average
> of multiple runs.
>
> Bug: 408449458
> Change-Id: I9556865a9f6b2acb7962a1b0c043d1e40d399c81
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6432910
> Reviewed-by: Kent Tamura <tkent@chromium.org>
> Commit-Queue: Koji Ishii <kojii@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1446951}

Bug: 410930625, 408449458
Change-Id: If2105100c295e38cebc6f7e3f47b0ef8ed8a7774
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6466944
Auto-Submit: Koji Ishii <kojii@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1448116}