Remove TransportSecurityState::AddOrUpdateEnabledPKPHosts.

Unused since https://crrev.com/230996f183bc6eb2f8ec2a39f7d19f9d6267ec84

Bug: 779166
Change-Id: I57e2f6253b834734829fd7acacc6254afbe07081
Reviewed-on: https://chromium-review.googlesource.com/c/1298418
Reviewed-by: David Benjamin <davidben@chromium.org>
Commit-Queue: Matt Mueller <mattm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602518}
2 files changed