Mac Photos.app has surprisingly deep editing features for an app that feels lightweight. (even if you have to click that "Add" button to get to some of them)
Editing options are initially limited (see above in the "before" shot). Clicking the Add button reveals new editing options; in this case, Vignette and White Balance. Other available options include Histogram, Sharpen, Definition, Noise Reduction, Levels, and an option to save the current Adjustments palette as the default one (see the "after" shot below).