function(icon, icon_size) {
        // do I have a platform icon for that density already
        var density = icon.density || sizeToDensityMap[icon_size];
        if (!density) {
            // invalid icon defition ( or unsupported size)
            return;
        }
        var previous = android_icons[density];
        if (previous && previous.platform) {
            return;
        }
        android_icons[density] = icon;
    }