Resource thresholds may soon be added for other process reuse policies,
so this CL starts to generalize the code added for the ProcessPerSite
main frame reuse threshold.
Specifically, the policy in use for the current case is now passed into
the resource check function, and the main frame threshold is only
referenced there and not passed through other functions anymore.
SiteIsolationImpl::ProcessReusePolicy has also moved into its own file,
to make it easier to use in more places.
Low-Coverage-Reason: TRIVIAL_CHANGE Refactor with no behavior change.
Bug: 40259123
Change-Id: Ic1448b68b8e5a6a2b33081849e67ee1c83019d3f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5837830
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Commit-Queue: Charlie Reis <creis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1351731}
