Got some very nice figures there. Thanks for posting.
If I read it right an average Cocker will have to eat best part of 2 pounds of Chocolate to get a fatal dose.
Somewhat less if it's the strong dark stuff.
Of course a lot less will be required to make them sick. I'd guess that a Cocker eating 2 pounds of chocolate will in fact sick it up quite quickly.
Tried calculating from pounds to grams and that seems like a really high amount. Isn't 2 pounds around 1kg? I would call the vet for much smaller amounts, even for milk chocolate. But I'm not familiar with lbs. Try this calculator to get an idea maybe.
http://www.petmd.com/dog/chocolate-toxicityFor dark chocolate I would call the vet and have them calculate for any amount as it is really very toxic. The symptoms of theobromine toxicosis is very unpleasant, so if at all unsure I would prefer to get treatment as quickly as possible. If you are quick enough then one injection to make the dog sick is all you need. If you wait until the chocolate is being absorbed from the intestines then the treatment i a lot more complicated. We rushed my girl in as soon as we could and she vomited up a huge amount, but she had been alone for a few hours and had already startet digesting and absorbing some of the chocolate. She was shaking, uncoordinated, confused, it was terrifying. She had to stay all night on a fluid drip until her neurological symptoms subsided. She also recieved pain medication and something for the nausea and something to protect the intestines. I was too scared to really pay attention, but it was a long night. Dark chocolate is now banned in my house (it was a houseguest that forgot to put away her chocolate).