Predator and CL could not provide any possible suspects.
Using Code Search for the file, "documentloader.cpp" assigning to the concern owner using GIT Blame.

Suspecting commit#
https://chromium.googlesource.com/chromium/src/+/0cca324ec82d5b59ba8b917f810d652e010b4e72

@japhet -- 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 497683:497686.

Detailed report: https://clusterfuzz.com/testcase?key=4615274275012608

Fuzzer: inferno_twister
Job Type: windows_syzyasan_chrome
Platform Id: windows

Crash Type: Null-dereference
Crash Address: 0x0000005f
Crash State:
  blink::DocumentLoader::InstallNewDocument
  blink::DocumentLoader::ReplaceDocumentWhileExecutingJavaScriptURL
  blink::FrameLoader::ReplaceDocumentWhileExecutingJavaScriptURL
  
Memory Tool: SYZYASAN

Regressed: https://clusterfuzz.com/revisions?job=windows_syzyasan_chrome&range=497582:497621
Fixed: https://clusterfuzz.com/revisions?job=windows_syzyasan_chrome&range=497683:497686

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=4615274275012608

See https://github.com/google/clusterfuzz-tools 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 4615274275012608 is verified as fixed, so closing issue as verified.

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