Linux: fix .desktop file lookup ("again").

BUG=303878
R=erg@chromium.org

Review URL: https://codereview.chromium.org/25737008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226856 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226856