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

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/80471d8d1cbf8b08eaa893832f4d735765881a02

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

Reproduced on Version 61.0.3147.0 (Official Build) canary (64-bit)

Working on relative task which fill fix this.

ClusterFuzz has detected this issue as fixed in range 485175:485183.

Detailed report: https://clusterfuzz.com/testcase?key=6099314006032384

Fuzzer: miaubiz_css_fuzzer
Job Type: windows_syzyasan_chrome
Platform Id: windows

Crash Type: Null-dereference
Crash Address: 0x00000027
Crash State:
  blink::SetSelectionState
  blink::UpdateLayoutObjectState
  blink::LayoutSelection::Commit
  
Memory Tool: SYZYASAN

Regressed: https://clusterfuzz.com/revisions?job=windows_syzyasan_chrome&range=483471:483525
Fixed: https://clusterfuzz.com/revisions?job=windows_syzyasan_chrome&range=485175:485183

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6099314006032384


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 6099314006032384 is verified as fixed, so closing issue.

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