I could have made those up
Actually both those terms were explained to me by native Brazilians upon inquiring about the lyrics of a popular song called
Chiclete com Banana (it juxtaposes unlikely combinations along the lines of our "when Hell freezes over" or "when pigs fly"). So that's a word-of-mouth source. But is it commonly known that Chiclets are made from chickle? I've never even heard of chickle - the thought being if the brand name is more widely known than the ingredient, that would seem a more likely etymology.
Frigideira for frying pan seems slightly more obscure to me- maybe they put that marque on more than refrigerators in Brazil, I dunno.
I agree, this question should be put to BD.