Try to work around bug in glib by ensuring DBUS_SESSION_BUS_ADDRESS is set.

BUG=309093
R=dtu@chromium.org

Review URL: https://codereview.chromium.org/42913002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230904 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230904