Move preferences_mac* into chrome/browser/policy/ directory.

BUG=50548
R=mnissler@chromium.org
TBR=darin@chromium.org

Review URL: https://chromiumcodereview.appspot.com/11926014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@177730 0039d316-1c4b-4281-b951-d872f2087c98
9 files changed