c5c4c87728
They currently fall back to the main Looper if the current thread doesn't have a Looper. All the changed Handlers are guaranteed to be created on a thread with a Looper (mostly the ExoPlayer playback Looper) and thus can make this stricter assumption. This makes it easier to reason about the code as there are no ambiguities as to which thread the Handler is running on. PiperOrigin-RevId: 317334503