[Chrome OS ECHO] Add cookies permission to extension and change intent disposition to inline

chrome/browser/resources/chromeos/offers/main.js

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-function couponCodeCallback(result) {
-  response = "getCouponCode returned: " + result;
-  console.log(response);
-}
-
-function consentCallback(result) {
-  if (result == true) {
-    chrome.offersPrivate.getCouponCode("COUPON_CODE", couponCodeCallback);
-    return;
-  }
-  console.log("User declined ECHO!");
-}
-
-window.onload = function() {
-  chrome.offersPrivate.getUserConsent(consentCallback);
-}