Before this change we checked whether the playback state and playWhenReady have changed when the state from the cast device arrived. If we detected such a change we called the listener callback `onIsPlayingChanged`. However, in the case when `setPlayWhenReady(boolean)` is called on 'CastPlayer', we mask the change in `playWhenReady`, then send the play/pause request to the cast device and when the state from the cast device arrives we never detect a change because we have already masked `playWhenReady`.
This change now moves the check for `isPlaying` to the same place where the state and playWhenReady is updated, so we call the `onIsPlayingChanged` callback in either case, when masking or when a changed state from the server arrives.
Issue: google/ExoPlayer#9792
PiperOrigin-RevId: 418483509
