Sydney Landau, in his book, Dictionaries: the Art and Craft of Lexicography (Cambridge U Press, 2001) says that the lexicographer "cannot allow any special-interest group to determine what gets in his dictionary or how it is represented" (page 407). That would seem to discourage McDonald's from being too pushy with lexicographers, who have their own methods of determining meaning and who don't much cater to external pressures from industry.
So, how are dictionaries compiled and what do lexicographers do? The latest update to the OED has just come out, and some of their experts talk about the new words and how they collect them here:
ENA5 – Language Change