Predator and CL could not provide any possible suspects.
Using the code search for the file, “window_tree_host.cc” assigning to concern owner from GIT revision log.
Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/e265d970d1b5dbe670badff34d4692d39714e58e

@sadrul  -- Could you please look into this issue, kindly reassign if it has nothing to do with your changes.
Thank You.

ClusterFuzz has detected this issue as fixed in range 503872:503913.

Detailed report: https://clusterfuzz.com/testcase?key=5322804718469120

Fuzzer: inferno_layout_test_unmodified
Job Type: windows_syzyasan_content_shell
Platform Id: windows

Crash Type: Null-dereference
Crash Address: 0x0000005f
Crash State:
  aura::client::GetCaptureWindow
  aura::WindowTreeHost::OnHostLostWindowCapture
  ui::WinWindow::_ProcessWindowMessage
  
Memory Tool: SYZYASAN

Regressed: https://clusterfuzz.com/revisions?job=windows_syzyasan_content_shell&range=441984:442831
Fixed: https://clusterfuzz.com/revisions?job=windows_syzyasan_content_shell&range=503872:503913

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5322804718469120

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.