Predator and CL did not provide any possible suspects.
Using Code Search for the file, "CompositeEditCommand.cpp" assigning to the concern owner from GIT Blame.
Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/34e20090704e62dbb27e402b116e5a0259c385ee

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

ClusterFuzz has detected this issue as fixed in range 472221:472281.

Detailed report: https://clusterfuzz.com/testcase?key=5871269320065024

Fuzzer: ochang_domfuzzer
Job Type: linux_tsan_chrome_mp
Platform Id: linux

Crash Type: CHECK failure
Crash Address: 
Crash State:
  false. Not supported input type on plain-text only element:37 in CompositeEditCo
  
Sanitizer: thread (TSAN)

Regressed: https://clusterfuzz.com/revisions?job=linux_tsan_chrome_mp&range=472186:472205
Fixed: https://clusterfuzz.com/revisions?job=linux_tsan_chrome_mp&range=472221:472281

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5871269320065024


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 5871269320065024 is verified as fixed, so closing issue.

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