Move PolicyErrorMap to components/policy/.

Facilitates policy componentization. Also add DEPS exceptions for ui
and grit includes.

BUG=271392
TBR=sky

Review URL: https://codereview.chromium.org/103263003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239004 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239004