When calling the methods
com_android_server_PersistentDataBlockService_getBlockDeviceSize()
com_android_server_PersistentDataBlockService_wipe()
memory is leaked because string created by
GetStringUTFChars() is not released.
Use ScopedUtfChars instead to ensure that memory is released.
Change-Id: I880a6d66a4824778b411b858774b8ffa009c1e17