MSE: Fix logic bugs with high precision duration

media/filters/chunk_demuxer.cc

Index: media/filters/chunk_demuxer.cc
diff --git a/media/filters/chunk_demuxer.cc b/media/filters/chunk_demuxer.cc
index 66eb09a011eb0c2f121d5fab0d69fbb79c001248..1edff064182e70886fadbf469cb46652ecad3123 100644
--- a/media/filters/chunk_demuxer.cc
+++ b/media/filters/chunk_demuxer.cc
@@ -1209,7 +1209,8 @@ bool ChunkDemuxer::IsValidId(const std::string& source_id) const {
 }
 
 void ChunkDemuxer::UpdateDuration(TimeDelta new_duration) {
-  DCHECK(duration_ != new_duration);
+  DCHECK(duration_ != new_duration ||
+         user_specified_duration_ != new_duration.InSecondsF());
   user_specified_duration_ = -1;
   duration_ = new_duration;
   host_->SetDuration(new_duration);
@@ -1249,8 +1250,12 @@ void ChunkDemuxer::DecreaseDurationIfNecessary() {
   if (max_duration.is_zero())
     return;
 
-  if (max_duration < duration_)
+  // Note: be careful to also check |user_specified_duration_|, which may have
+  // higher precision than |duration_|.
+  if (max_duration < duration_ ||
+      max_duration.InSecondsF() < user_specified_duration_) {
     UpdateDuration(max_duration);
+  }
 }
 
 Ranges<TimeDelta> ChunkDemuxer::GetBufferedRanges() const {