commit 993f6cc1569f96df1fd32c67c1251b992dfd61b9
author Scott Haseley <shaseley@chromium.org> Fri Jan 06 16:48:35 2023
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Fri Jan 06 16:48:35 2023
tree fff0befa282f209dac0851a8b37e4b0346a7dc3d
parent 72b971e3d9bd6ebac6288bb5766c494649b5b08d

[dom] Implement AbortSignal.any() prototype

This adds the basic functionality for AbortSignal.any(), which creates
a new signal that will be aborted if any of the signals associated
signals are aborted. The API is implemented behind a flag.

The general idea and concepts are:
 - A signal created with this API is a "composite signal", composed of
   0 or more "abort sources".
 - An abort source can be any AbortSignal, but since the relationships
   are established at signal creation time, we can link to non-composite
   signals, i.e. those associated with a controller.
 - If any of the abort sources are already aborted when this API is
   called, it returns an aborted signal (with the culprit's reason).
 - During SignalAbort, a signal will invoke SignalAbort on all of its
   "dependent signals" (those for which it is a source).

Most of this is implemented by AbortSignalCompositionManager. In this CL
this class handles linking source/dependent abort signals, but in
follow-up CLs this will also:

 1. Also manage priority sources for composite TaskSignals, which are
    created by a specialization for TaskSignal.any(). The logic for
    managing abort and priority sources/dependents is the same, so this
    setup is optimized for code reuse. Note also that the WPT tests for
    for AbortSignal.any() are implemented in resources/ and pulled in
    via META statements for reuse with TaskSignal.any().

 2. Handle more complex memory management. Memory leaks can result from
    composite signals following long-lived top-level signals, which we
    expect to be a common pattern and part of the motivation for the UA
    maintaining the signal relationships. This is separated out to keep
    CLs smaller.

Explainer: https://github.com/shaseley/abort-signal-any
I2P: https://groups.google.com/a/chromium.org/g/blink-dev/c/FSH6hrJMaxM/m/Ft8KiGlbAAAJ
Design doc: https://docs.google.com/document/d/1LvmsBLV85p-PhSGvTH-YwgD6onuhh1VXLg8jPlH32H4/edit?usp=sharing

Bug: 1323391
Change-Id: Ibc85815b166fd4242543f30600be99fadf35992e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3703640
Reviewed-by: Nate Chapin <japhet@chromium.org>
Reviewed-by: Mason Freed <masonf@chromium.org>
Commit-Queue: Scott Haseley <shaseley@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1089752}