Move URLBlacklistManager to components/policy.

This enables building that class on the iOS build.

BUG=271392
TBR=joaodasilva@chromium.org

Review URL: https://codereview.chromium.org/102973005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241421 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241421