Bug 1501665 patches relax the requirement that the apz.allow_zooming pref must be true to allow resolution zooming. This is so documents displayed in an RDM pane can also be zoomed. All of the callsites for APZAllowZooming() probably should convert to calls to the new AllowZoomingForDocument() function. There may be exceptions. Those callsites may need additional changes in order to have access to a relevant Document pointer.