Predator and CL did not provide any possible suspects.
Using Code Search for the file, "ArrayBufferContents.cpp" assigning to the concern owner.

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/4bcb9954c02c7dd9c7cb2a0756e4a3002ec66e5d

@jbroman -- Could you please look into the issue, kindly re-assign if this is not related to your changes.
Thank You.

Proximate cause seems to be SharedArrayBuffer enabling:
https://chromium.googlesource.com/chromium/src/+/ac2ac7b771c7d5838b4e2e35523bf38d215ac926

Seems the memory accounting code (last modified by sigbjornf@opera.com) doesn't handle shared buffers well.

ClusterFuzz has detected this issue as fixed in range 484701:484715.

Detailed report: https://clusterfuzz.com/testcase?key=6581463150755840

Fuzzer: inferno_layout_test_unmodified
Job Type: linux_debug_content_shell_drt
Platform Id: linux

Crash Type: CHECK failure
Crash Address: 
Crash State:
  !has_registered_external_allocation_ in ArrayBufferContents.cpp
  blink::SerializedScriptValue::RegisterMemoryAllocatedWithCurrentScriptContext
  blink::MessageEvent::MessageEvent
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=linux_debug_content_shell_drt&range=471544:471546
Fixed: https://clusterfuzz.com/revisions?job=linux_debug_content_shell_drt&range=484701:484715

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6581463150755840


See https://dev.chromium.org/Home/chromium-security/bugs/reproducing-clusterfuzz-bugs for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

ClusterFuzz testcase 6581463150755840 is verified as fixed, so closing issue.

If this is incorrect, please add ClusterFuzz-Wrong label and re-open the issue.