A bit more methodical approach to IDing this plant:
Opposite leaves + a corymb of multiple dark-colored, round drupes is very indicative of the genus Viburnum.
If we check BONAP and Ontario Trees & shrubs, we can see that only a handful of Viburnum species are found in Ontario.
From Ontario Trees & shrubs:
- Viburnum alnifolium (Hobblebush)
- Viburnum dentatum (Smooth Arrowwood)
- Viburnum lantanoides (Hobblebush)
- Viburnum lentago (Nannyberry)
- Viburnum nudum (Wild Raisin)
- Viburnum rafinesqueanum (Downy Arrowwood)
- Viburnum recognitum (Smooth Arrowwood)
(BONAP additionally shows V. acerifolium, V. lantana, V. edule, and V. opulus).
If we examine images of each of these (found by following the links at Ontario Trees & shrubs), we can see that the majority have the wrong leaf shape or leaf margin (i.e., toothiness). In fact, of all the viburnum species listed, Viburnum lentago (Nannyberry) is the only one that appears morphologically similar to the OP's specimen.
So as Peter1807's answer suggests, this is very likely a native shrub to Ontario called Viburnum lentago (commonly called Nannyberry).
Source: Demeter's Dish
Are they edible??
According to Ontario Trees & shrubs, the fruit are edible. Amy over at Demeter's Dish provides the following taste profile:
The taste is mildly raisin-like. Slightly sweet and with a not-unpleasant grainy texture, similar to dates.