Make sure we always hide content_window_ when hiding a DNWA

For certain window types, DNWA's content_window_ wasn't being hidden immediately when DNWA::Close() is called. Instead just the HWND attached to the DRWHWin was being hidden. The side-effect of this was that attached controllers (like FocusController) weren't being told to update their bookkeeping until much later in the destruction process which I think is leading to crashes. This change makes the hiding more like ChromeOS.

R=sky@chromium.org
http://crbug.com/314118

Review URL: https://codereview.chromium.org/61003008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234941 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234941