Unify the Windows Parental Controls Platform Caching

There were two caches running around for Windows Platform Controls caching. One lived in the incognito mode prefs and the other lived in the Windows code. This change unifies both caches for easier management.

BUG=458388
TBR=rogerta

Review URL: https://codereview.chromium.org/969813005

Cr-Commit-Position: refs/heads/master@{#319482}
6 files changed