GTK: Fix valgrind errors in previous wmclass patch.

(Can't actually read that field; need to use the glib accessor.)

BUG=80282,20587
TEST=valgrind goes green.

Review URL: http://codereview.chromium.org/6896028

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@82672 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed