It seems to mean that she wore a Chanel garment, in which case do you say "she wore Chanel" or "she wore a Chanel"?The first time that Kristen wore Chanel for a public appearance was at the Toronto Film Festival in 2007 and she has done so on several occasions since, including the Met Ball in 2010 and at the Chanel Haute Couture fashion show in July 2013.
-Just Jared