Potential issues:
1. postpones Close() call during Read()s but not Rewind()s
2. if Close() is postponed (i.e. mDestroyAdapterPostponed is true), Close() only seems to be called if onError() or onReadSucceeded() are called, but not if onRewindSucceeded() is called or if the embedder cancels the request and never calls onReadSucceeded() or other final callbacks.

I'm not sure if this is by design or a bug.