New device policies for enterprise auto-update controls.

Enterprise admins need more control over the auto-update behavior
of ChromeOS. This CL adds two policies which will provide such
control, one for disabling updates and another for pinning a
device to a particular target version.

BUG=chromium-os:27307
TEST=Update_engine client code builds with new policies.

Review URL: http://codereview.chromium.org/9701047

git-svn-id: http://src.chromium.org/svn/trunk/src/chrome/browser/policy/proto@127108 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
1 file changed