Pass correct object_type in AddKnownSidToObject

The correct DACL wasn't being set on the winstation.

BUG=347849
R=cpu
TBR=cpu

Review URL: https://codereview.chromium.org/180513006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255065 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255065