RFR (S): 8243974: Move G1CollectedHeap::millis_since_last_gc support from G1Policy

[Kim Barrett]

> On Jun 25, 2020, at 3:39 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi all,
> 
>  please review the following change that moves G1CollectedHeap::millis_since_last_gc support away from G1Policy to G1CollectedHeap. That functionality has not much to do with policy decisions at all.
> 
> Fwiw, found the issue 8248221 when fixing this. Will send out that one soon.
> 
> Based on 8165501.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8243974
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8243974/webrev/
> Testing:
> tier1-5 with 8165501, 8248221; see also 8248221 for manual testing info
> 
> Thanks,
>  Thomas

Looks good.