Queen to annouce Canada's next Governor General?

The Queen is set to announce the next Governor General of Canada during her tour. Apparently the favoured candidate is David Lloyd Johnston. Interestingly, this will be one of the few times the Queen has annouced her own representative - usually it's done by the Prime Minister. The last time it seems to have happened was in New Zealand in 1977, when Sir Keith Holyoake, then a sitting member of cabinet, was appointed to the role.