Predator and CL did not provide any possible suspect.
Using Code Search for the file, "render_frame_impl.cc" assigning to the concern owner who might be related.

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

ClusterFuzz has detected this issue as fixed in range 467299:467309.

Detailed report: https://clusterfuzz.com/testcase?key=4605944534401024

Fuzzer: lcamtuf_cross_fuzz
Job Type: mac_asan_chrome
Platform Id: mac

Crash Type: CHECK failure
Crash Address: 
Crash State:
  result.second. Inserting a duplicate item in render_frame_impl.cc
  content::RenderFrameImpl::RenderFrameImpl
  content::RenderFrameImpl::CreateMainFrame
  
Sanitizer: address (ASAN)

Fixed: https://clusterfuzz.com/revisions?job=mac_asan_chrome&range=467299:467309

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=4605944534401024


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 4605944534401024 is verified as fixed, so closing issue.

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