This is very simple one. If Aggie will play her worst and Heather her best, Heather has a chance. If Aggie will play close to her best, and Heather too, i see 6;4 6;3 for Aggie. If Aggie will play close to her best and Heather her worse game, i see bagel+breadstick or double breadstick for Aggie.
But for me chances are like 95% Aggie 5% Heather because we can't compare good grass court player and current world no.3 against world no.103 without big successes, on a start of her career... This round is Heather's big achievement, but for me now she will receive a lesson of patience and consistence from most consistent and patient player of the world at the moment.