trying to extend whole findbar

bootstrap.js

const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
const self = {
	name: 'MatchWord',
	path: {
		chrome: 'chrome://matchword/content/'
	},
	aData: 0,
};
const myServices = {};
var cssUri;
var cssUriRemove;

Cu.import('resource://gre/modules/Services.jsm');
Cu.import('resource://gre/modules/devtools/Console.jsm');
Cu.import('resource://gre/modules/XPCOMUtils.jsm');
XPCOMUtils.defineLazyGetter(myServices, 'sss', function(){ return Cc['@mozilla.org/content/style-sheet-service;1'].getService(Ci.nsIStyleSheetService) });

function startup(aData, aReason) {
	self.aData = aData;
	console.log('aData',aData);
	var css = '.findbar-container { -moz-binding:url("' + self.path.chrome + 'findbar.xml#matchword") }';
	var cssEnc = encodeURIComponent(css);
	var newURIParam = {
		aURL: 'data:text/css,' + cssEnc,
		aOriginCharset: null,
		aBaseURI: null
	}
	cssUri = Services.io.newURI(newURIParam.aURL, newURIParam.aOriginCharset, newURIParam.aBaseURI);
	myServices.sss.loadAndRegisterSheet(cssUri, myServices.sss.USER_SHEET);
	
	var css = '.findbar-container { -moz-binding:url("' + self.path.chrome + 'findbar.xml#matchword_shutdown") }';
	var cssEnc = encodeURIComponent(css);
	var newURIParam = {
		aURL: 'data:text/css,' + cssEnc,
		aOriginCharset: null,
		aBaseURI: null
	}
	cssUriRemove = Services.io.newURI(newURIParam.aURL, newURIParam.aOriginCharset, newURIParam.aBaseURI);
	
	
}

function shutdown(aData, aReason) {
	if (aReason == APP_SHUTDOWN) return;
	myServices.sss.unregisterSheet(cssUri, myServices.sss.USER_SHEET);
	myServices.sss.loadAndRegisterSheet(cssUriRemove, myServices.sss.USER_SHEET);
}

function install() {}

function uninstall() {}

findbar.xml

<?xml version="1.0"?>
<bindings xmlns="http://www.mozilla.org/xbl" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
    <binding id="matchword">
        <content>
            <children/>
            <xul:toolbarbutton anonid="matchwordbtn" accesskey="w" class="tabbable" label="Match Word" tooltiptext="Match only whole words" oncommand="console.log('hi')" type="checkbox"/>
        </content>
    </binding>
    <binding id="matchword_shutdown">
        <content>
            <children/>
        </content>
    </binding>
</bindings>

gistfile1.txt

<?xml version="1.0"?>
<bindings xmlns="http://www.mozilla.org/xbl" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
    <binding id="matchword" extends="chrome://global/content/bindings/findbar.xml#findbar">
        <content>
			<children/>
			<xul:toolbarbutton anonid="matchwordbtn" accesskey="w" class="tabbable" label="Match Word" tooltiptext="Match only whole words" oncommand="console.log('hi')" type="checkbox"/>
        </content>
    </binding>
</bindings>