The necessity to destroy an ALC context is not to leave a leaking context as Context instances are being collected. If the user doesn't Destroy, do it when finalizing. If a context is destroyed by the user, a finalizer is no more needed. Change-Id: If6330361f7983ec8ede0e93b7f6e3a440de9fd6c Reviewed-on: https://go-review.googlesource.com/8497 Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>