bitwarden-browser/src/popup/app/services/backgroundService.js

angular
    .module('bit.services')

    .factory('tokenService', function () {
        return chrome.extension.getBackgroundPage().tokenService;
    })
    .factory('cryptoService', function () {
        return chrome.extension.getBackgroundPage().cryptoService;
    })
    .factory('userService', function () {
        return chrome.extension.getBackgroundPage().userService;
    });