RFR(M): 8218049: Survivor MemoryMXBean used() size granularity is region based

[Kim Barrett]

> On Apr 4, 2019, at 5:06 PM, sangheon.kim at oracle.com wrote:
> http://cr.openjdk.java.net/~sangheki/8218049/webrev.4
> http://cr.openjdk.java.net/~sangheki/8218049/webrev.4_inc/
> 
> Thanks,
> Sangheon

Looks good.