chore: cherry-pick a5f54612590d from chromium

[ppontes]

M96: Storage Foundation: Avoid cross-thread access of DOMArrayBufferView.

blink::NativeIOFile::{read, write}() (in the Storage Foundation API
implementation) pass DOMArrayBufferView instances to
blink::NativeIOFile::Do{Read,Write}() via CrossThreadPersistent.
blink::NativeIOFile::Do{Read,Write}() accesses these instances.

CrossThreadPersistent can be used across threads to keep a garbage
collected object alive. However, accessing the object on a different
thread is not safe. cppgc::subtle::CrossThreadPersistent
(blink::CrossThreadPersistent is an alias to that) has comments
explaining that the garbage collected heap can go away while the
CrossThreadPersistent instance exists.

This CL bypasses the problem by having Do{Read,Write}() receive a
ArrayBufferContents that has the DOMArrayBufferView's backing buffer.
ArrayBufferContents is not garbage-collected, so it can be safely used
across threads.

This CL introduces a NativeIODataBuffer class that contains the logic
and state for tearing a DOMArrayBufferView apart into its components
(backing buffer, view type, view offset, view length) and putting it
back together into a new DOMArrayBufferView, after it doesn't need to be
accessed cross-thread anymore.

(cherry picked from commit 5200793c2aea5979cc79f3350a4e3d6c0795d6f2)

Bug: 1268274
Change-Id: I51588f5bfe963de96ce426e0f480e8c5b4902688
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3269366
Commit-Queue: Victor Costan pwnall@chromium.org
Reviewed-by: enne enne@chromium.org
Reviewed-by: Joshua Bell jsbell@chromium.org
Cr-Original-Commit-Position: refs/heads/main@{#940070}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3272377
Bot-Commit: Rubber Stamper rubber-stamper@appspot.gserviceaccount.com
Cr-Commit-Position: refs/branch-heads/4664@{#941}
Cr-Branched-From: 24dc4ee75e01a29d390d43c9c264372a169273a7-refs/heads/main@{#929512}

Notes: Backported fix for CVE-2021-38011.

[jkleinsc]

Merging as CI failures are unrelated to PR change.

[release-clerk]

Release Notes Persisted

Backported fix for CVE-2021-38011.