Extractors should not report additional tracks once they called
ExtractorOutput.endTracks. This causes thread safety issues in
ProgressiveMediaPeriod where the array of sample queues is
extended while the playback thread accesses the arrays.
Detecting this problem early is beneficial to avoid unexplained
exceptions later one. In most cases where this may happen (namely
TS extractors finding new tracks), it's better to ignore the new
tracks instead of failing completely. So this change adds a
warning log message and assigns a placeholder output.
Note: The same workaround already exists in HlsSampleStreamWrapper
and MediaExtractorCompat.
Issue: androidx/media#1476
#cherrypick
PiperOrigin-RevId: 646427213
18e631ff79