Is it possible to make access to Browser API from the User-Script code? At least for Chrome-like browser.

Sometimes this really is really not enough and I do not want to write everytime extra extensions for the sake of a couple of lines of code.

Similar to:

    var filter = {urls: ["http://*/*", "https://*/*"], tabId: currentTabId };
    var opt_extraInfoSpec = ['blocking'];
    GM_webRequest.onBeforeRequest.addListener(
        callback, filter, opt_extraInfoSpec);