All the features are pure JS, and most of the integration API are common to both Firefox and Chrome. There should be few work to do so that it works on both browsers.
There is some work to complete with the data structures passed between the background and content scripts (circular objets are not serialized correctly in JSon).
There is also a bug in Chrome, that requires users to save all their download in the same folder, rather than being asked where to save every new download.
All the features are pure JS, and most of the integration API are common to both Firefox and Chrome. There should be few work to do so that it works on both browsers.