*** Reason for rollforward *** Rollforward after making sure the handler is created, and that a test is written preventing a similar regression. *** Original change description *** Rollback of https://github.com/google/ExoPlayer/commit/b6f5a263f725089c026bb8416ade555f4f16a2bc *** Original commit *** Rollforward of commit 5612ac50. *** Reason for rollforward *** Rollforward after making sure the handler is created from the playback thread and not from an app thread. *** Original change description *** Rollback of https://github.com/google/ExoPlayer/commit/e1beb1d1946bb8ca94f62578aee8cbadd97b6e2b *** Original commit *** PiperOrigin-RevId: 318274400
