Adding `content_security_policy` to a few sample extensions.

chrome/common/extensions/docs/examples/howto/contentscript_xhr/contentscript.js

 /*
 * Copyright (c) 2011 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.
 */
 
 /**
  * Performs an XMLHttpRequest to Twitter's API to get trending topics.
  *
  * @param callback Function If the response from fetching url has a
  *     HTTP status of 200, this function is called with a JSON decoded
  *     response.  Otherwise, this function is called with null.
  */
 function fetchTwitterFeed(callback) {
   var xhr = new XMLHttpRequest();
   xhr.onreadystatechange = function(data) {
     if (xhr.readyState == 4) {
       if (xhr.status == 200) {
         var data = JSON.parse(xhr.responseText);
         callback(data);
       } else {
         callback(null);
       }
     }
   }
   // Note that any URL fetched here must be matched by a permission in
   // the manifest.json file!
-  var url = 'https://api.twitter.com/1/trends.json?exclude=hashtags';
+  var url = 'https://api.twitter.com/1/trends/daily.json?exclude=hashtags';
   xhr.open('GET', url, true);
   xhr.send();
 };
 
 /**
  * Parses text from Twitter's API and generates a bar with trending topics at
  * the top of the current page
  *
  * @param data Object JSON decoded response.  Null if the request failed.
  */
 function onText(data) {
   // Only render the bar if the data is parsed into a format we recognize.
   if (data.trends) {
     // Create the overlay at the top of the page and fill it with data.
     var trends_dom = document.createElement('div');
     var title_dom = document.createElement('strong');
     title_dom.innerText = 'Topics currently trending on Twitter:';
     trends_dom.appendChild(title_dom);
-    for (var i=0,trend; trend = data.trends[i]; i++) {
-      var link_dom = document.createElement('a');
-      link_dom.setAttribute('href', trend.url)
-      link_dom.innerText = trend.name;
-      link_dom.style.color = '#000';
-      trends_dom.appendChild(document.createTextNode(' '));
-      trends_dom.appendChild(link_dom);
+    for (var key in data.trends) {
+      for (var i=0,trend; trend = data.trends[key][i]; i++) {
+        var link_dom = document.createElement('a');
+        link_dom.setAttribute('href', trend.url)
+        link_dom.innerText = trend.name;
+        link_dom.style.color = '#000';
+        trends_dom.appendChild(document.createTextNode(' '));
+        trends_dom.appendChild(link_dom);
+      }
+      break;
     }
     trends_dom.style.cssText = [
       'background-color: #ffd700;',
       'background-image: -webkit-repeating-linear-gradient(' +
           '45deg, transparent, transparent 35px,' +
           'rgba(0,0,0,.1) 35px, rgba(0,0,0,.1) 70px);',
       'color: #000;',
       'padding: 10px;',
       'font: 14px Arial;'
     ].join(' ');
     document.body.style.cssText = 'position: relative';
     document.body.parentElement.insertBefore(trends_dom, document.body);
   }
 };
 
 fetchTwitterFeed(onText);