adj.
fed-up, annoyed.
Partridge's Dictionary of Slang and Unconventional English (DS-5) states the term originates from the Royal Air Force, ca. 1920, and marks it "slightly ob[solete]". The 1941 quotation (below) also references the Royal Air Force, indicating preservation of the term from Britain. Browned off is not limited to Canada (see Chart 1), but is most prevalent in Ireland, with some currency in Commonwealth countries, and also in the US.
See COD-2, s.v. "browned off", which is marked "Cdn & Brit," and "slang", and OED-3, s.v. "browned" (2), which is marked "slang", W-3, s.v. "browned-off", which is marked "slang", DS-5, s.v. "brown off".