RFR: 8292266: Add JFR event for total Reference processing time

[Sangheon Kim]

Hi all,

Can I have reviews for this change that adds a new JFR event for total Reference Processing time?

The goal is to generate a new JFR event if there is already measured time. This CR doesn't add new time measurement.

Testing: hs-tier1 ~ 3

Thanks,
Sangheon

-------------

Commit messages:
 - Remove comment out code.
 - Combine GCTrace::report method.
 - Separate GCTrace::report method.

Changes: https://git.openjdk.org/jdk/pull/11230/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11230&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292266
  Stats: 141 lines in 11 files changed: 135 ins; 2 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/11230.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11230/head:pull/11230

PR: https://git.openjdk.org/jdk/pull/11230