Revert r229404 "Refactored the policy code to avoid BrowserThread."
Landed by hand, w/ no try bots, broke tree.

Review URL: https://codereview.chromium.org/29173002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229411 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229411