[NAN] Update finalize to check and warn user if resources not freed

Use CloseGuard to check that disconnect() is called to free the resources
allocated by connect(). finalize() will still call disconnect() but now
also print out errors (if StrictMode enabled for feature).

Bug: 28068773
Change-Id: I5f5847c0261ef9f79a21fdb935509a85761591cc
2 files changed