Check policy existence in NELServiceImpl::OnPoliciesLoaded

There might be duplicate entries in the store, so let's check that.

Bug: 1326282
Change-Id: Id9032d9a9b956282063401206c2eed5e669ec2cf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3655158
Reviewed-by: Mason Freed <masonf@chromium.org>
Reviewed-by: Kunihiko Sakamoto <ksakamoto@chromium.org>
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1005532}
NOKEYCHECK=True
GitOrigin-RevId: 0f2461580860d1e1b1bfc5b4e21da25974571fc3
2 files changed