If LoadControl.shouldContinueLoading returns false and the renderers are not
ready for playback using the already buffered data, playback is stuck.
To prevent this situation, we always continue loading if the buffer is almost
empty. We already have a similar workaround for when
LoadControl.shouldStartPlayback returns false even if loading stopped.
Having both workarounds allows playback to continue even if the LoadControl
tries to prevent loading and playing all the time.
PiperOrigin-RevId: 283516750
b84bde0252