Remove TabContents from TabStripModelObserver::TabDetachedAt.

BUG=107201
TEST=no visible change


Review URL: https://chromiumcodereview.appspot.com/11293205

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@167122 0039d316-1c4b-4281-b951-d872f2087c98
gboolean TabStripGtk::OnDragMotion(GtkWidget* widget, GdkDragContext* context,
                                   gint x, gint y, guint time) {
  UpdateDropIndex(context, x, y);
  return TRUE;
}

gboolean TabStripGtk::OnDragMotion(GtkWidget* widget, GdkDragContext* context,
                                   gint x, gint y, guint time) {
  UpdateDropIndex(context, x, y);
  return TRUE;
}
