Predator and CL could not provide any possible suspects.
Using Code SEarch for the file, "track_run_iterator.cc" assigning to the concern owner.

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/f40f65fcd5154127ca5e7a354b2c3a2ba779d8bc

@wolenetz -- 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 498180:498221.

Detailed report: https://clusterfuzz.com/testcase?key=6386913388003328

Fuzzer: libFuzzer_mediasource_MP4_FLAC_pipeline_integration_fuzzer
Job Type: libfuzzer_chrome_asan
Platform Id: linux

Crash Type: Floating-point-exception
Crash Address: 
Crash State:
  media::mp4::TimeDeltaFromRational
  media::mp4::MP4StreamParser::ParseMoov
  media::mp4::MP4StreamParser::ParseBox
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan&range=497063:497144
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan&range=498180:498221

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6386913388003328

See https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/reproducing.md 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 6386913388003328 is verified as fixed, so closing issue as verified.

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

I believe I fixed this with https://chromium-review.googlesource.com/639329 (r498196), that also fixed a similar issue tracked by  bug 758876 .