Add chrome://site-tiles-internals/

components/ntp_tiles/webui/resources/ntp_tiles_internals.js

+// Copyright 2016 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.
+
+cr.define('chrome.ntp_tiles_internals', function() {
+  'use strict';
+
+  var initialize = function() {
+    receiveSites({});
+
+    $('submit-update').addEventListener('click', function(event) {
+      event.preventDefault();
+      chrome.send('update', [{
+        "popular": {
+          "overrideURL": $('override-url').value,
+          "overrideCountry": $('override-country').value,
+          "overrideVersion": $('override-version').value,
+        },
+      }])
+    });
+
+    chrome.send('registerForEvents');
+  }
+
+  var receiveSourceInfo = function(state) {
+    jstProcess(new JsEvalContext(state), $('sources'));
+  }
+
+  var receiveSites = function(sites) {
+    jstProcess(new JsEvalContext(sites), $('sites'));
+  }
+
+  // Return an object with all of the exports.
+  return {
+    initialize: initialize,
+    receiveSourceInfo: receiveSourceInfo,
+    receiveSites: receiveSites,
+  };
+});
+
+document.addEventListener('DOMContentLoaded',
+                          chrome.ntp_tiles_internals.initialize);
+