Cochrane burst on to the scene as a 16-year-old and famously netted his first goal for the club when Hearts ended Celtic's 69-game unbeaten run with a 4-0 victory at Tynecastle.
He was a regular part of his first-team squad in his debut season but he found it more difficult last time round, thanks to a combination of greater strength in depth and niggling injury problems.
McDonald spent the latter half of last season at Inverness CT. Similar to McDonald, he found first-team opportunities tougher in the 2018/19 season compared with his debut campaign.
He impressed in the 2-0 away win to Cowdenbeath in the Betfred Cup but hasn't featured since the following match against Stenhousemuir.