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/+/15d1b34174529968cac05a8902c96368687a8fd4

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

I think this is either the same issue as 758810, or something related. Matt, PTAL

Yes, duplicate root cause as  bug 758810  (just hits the DCHECK first due to build type).

numer=0x900000002000000, denom=0xac44
0xa=d5febf02110
Check failed: (a > 0 ? a : -a) <= std::numeric_limits<int64_t>::max() / base::Time::kMicrosecondsPerSecond (14705631437072 vs. 9223372036854)

=>sandersd@ for fix

In #4, fixed edit of cut&paste line is:
a=0xd5febf02110

ClusterFuzz has detected this issue as fixed in range 499783:499873.

Detailed report: https://clusterfuzz.com/testcase?key=4844342597648384

Fuzzer: libFuzzer_mediasource_MP4_FLAC_pipeline_integration_fuzzer
Job Type: libfuzzer_chrome_asan_debug
Platform Id: linux

Crash Type: CHECK failure
Crash Address: 
Crash State:
  (a > 0 ? a : -a) <= std::numeric_limits<int64_t>::max() / base::Time::kMicroseco
  base::debug::DebugBreak
  media::mp4::TimeDeltaFromRational
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=497039:497107
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=499783:499873

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=4844342597648384

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.