originfox/addon/background.js

function onResponse(response) {
    if (!response.success) {
        console.error("Error setting attributes");
    }
}

function onError(error) {
    console.log(`Error: ${error}`);
}

function handleChanged(delta) {
    if (delta.state && delta.state.current === "complete") {
        browser.downloads
            .search({
                id: delta.id,
            }).then(downloads => {
            let download = downloads[0];
            browser.runtime.sendNativeMessage("originfox", {
                path: download.filename,
                origin: download.url,
                referrer: download.referrer,
            }).then(onResponse, onError);
        });


    }
}

browser.downloads.onChanged.addListener(handleChanged);