There is race between SoundPoolThread and SoundPool / AudioManager
threads during releasing SoundPool.
AudioManager deletes a global reference before setting SoundPool
callback to NULL. If, at that time, a call to the SoundPool::notify
fuction happens then mCallback is valid but mUserData is not.
The following log will show up to indicate the problem:
JNI ERROR (app bug): accessed deleted global reference 0xXXXXXXXX
This fix is to clear the SoundPool's callback before releasing global
reference.
Change-Id: I5e6d647edc0444340db879428048e2c0a068a8b4
ed86e19af2