A long time ago, Tim wrote a post about the difficulties of getting new auto-dimming rearview side mirrors. I wrote a short add about the mirrors getting back in stock.
The brownish color was not the biggest issue, it was the failure of the dimming function on all mirrors. In November 2015 I fixed my left mirror it has worked fine ever since.
The auto dimming area does not cover the entire glass. However, that is nothing which you will notice driving the car. The auto dimming function works fine on all mirrors after I replaced the bad one.