commit d6d7515a63a09a6e8abe6c6e9d90a827fc83051f
author luci-bisection@appspot.gserviceaccount.com <luci-bisection@appspot.gserviceaccount.com> Tue Jul 01 14:50:57 2025
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue Jul 01 14:50:57 2025
tree 2032fd82c516f7d8df5a9f13c977cd0c8ac20be3
parent 39560f5a603b316e9fd3428c0c487622aa1556ce

Revert "platform: Improve modification performance of HeapObserverList"

This reverts commit e5eb677d594ad07d109441556592bfd62b9fd3f0.

Reason for revert:
LUCI Bisection has identified this change as the cause of a test failure. See the analysis: https://ci.chromium.org/ui/p/chromium/bisection/test-analysis/b/6252732630433792

Sample build with failed test: https://ci.chromium.org/b/8710567560535674017
Affected test(s):
[ninja://chrome/test:browser_tests/MessagingApiTest.LargeMessages](https://ci.chromium.org/ui/test/chromium/ninja:%2F%2Fchrome%2Ftest:browser_tests%2FMessagingApiTest.LargeMessages?q=VHash%3Addee393e1fa4b060)

If this is a false positive, please report it at http://b.corp.google.com/createIssue?component=1199205&description=Analysis%3A+https%3A%2F%2Fci.chromium.org%2Fui%2Fp%2Fchromium%2Fbisection%2Ftest-analysis%2Fb%2F6252732630433792&format=PLAIN&priority=P3&title=Wrongly+blamed+https%3A%2F%2Fchromium-review.googlesource.com%2Fc%2Fchromium%2Fsrc%2F%2B%2F6479957&type=BUG

Original change's description:
> platform: Improve modification performance of HeapObserverList
>
> Since https://crrev.com/15370ec03c1a44797aa2287807e3acdd78b70f0d the
> list of observers is managed with a dense vector instead of a hash set
> to allow fast iteration. This is useful as the set is iterated on e.g.
> DOM modifications in rendering hot paths.
>
> This CL adds back the hashmap with a mapping from observer to index in
> the vector to allow for amortized constant time add and remove.
> Especially remove could otherwise suffer from O(N) handling with e.g.
> lots of (>10^6) queued setTimeout() calls.
>
> Bug: 411573537
> Change-Id: Iafd5c4a2f3021fd7617324fbcaa03a85438950d4
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6479957
> Reviewed-by: Omer Katz <omerkatz@chromium.org>
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1480870}
>

Bug: 411573537
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: I498805768e86eea5654a3b2e9bb61e94737d8b68
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6696744
Commit-Queue: Mahmoud Rashad <mmrashad@google.com>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Mahmoud Rashad <mmrashad@google.com>
Cr-Commit-Position: refs/heads/main@{#1481053}