chore: cherry-pick db71a0afc1d0 from chromium

[nornagon]

Clear context from orphan handlers when BaseAudioContext is going away

When preparing to collect a BaseAudioContext, go through all the
rendering_orphan_handlers_ and deletable_orphan_handlers_ and remove
the context from the handler. This ensures that these handlers no
longer have references to the context when the BaseAudioContext is
destroyed because in some cases, these orphan handlers will get pulled
and access the context, which is already gone.

Clearing these in a prefinalizer ensures these orphan handlers don't
try to touch the context.

Manually verified that the repro case no longer reproduces.

Bug: 1062247
Change-Id: I50d083743903eb9544e09aa1ee912fc880331501
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2107806
Reviewed-by: Kentaro Hara haraken@chromium.org
Reviewed-by: Hongchan Choi hongchan@chromium.org
Commit-Queue: Raymond Toy rtoy@chromium.org
Cr-Commit-Position: refs/heads/master@{#751814}

Notes: Security: backported fix for use-after-poison in WebAudio.

[deepak1556]

Failing tests are not related

[release-clerk]

Release Notes Persisted

Security: backported fix for use-after-poison in WebAudio.