hideHangoutsInInbox.js

// ==UserScript==
// @name         Hide Hangouts in Inbox
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       Justin Force
// @match        https://inbox.google.com/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    var selectors = {
        button: '[title=Hangouts][role=button]',
        chatWindows: 'iframe[src^="https://hangouts.google.com"]'
    };

    function hide(element) {
        console.log(element);
        element.style.opacity = 0;
        element.style.pointerEvents = 'none';
    }

    function hideChatWindows() {
        document.querySelectorAll(selectors.chatWindows).forEach(function(iframe) {
            hide(iframe);
        });
    }

    function hideButton() {
        hide(document.querySelector(selectors.button).parentNode.parentNode);
    }

    function init() {
        setInterval(function () {
            hideButton();
            hideChatWindows();
        }, 500);
    }

    init();
})();