Adding `content_security_policy` to the "Mappy" sample.

chrome/common/extensions/docs/examples/extensions/mappy/mappy_content_script.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.
+
 // The background page is asking us to find an address on the page.
 if (window == top) {
   chrome.extension.onRequest.addListener(function(req, sender, sendResponse) {
     sendResponse(findAddress());
   });
 }
 
 // Search the text nodes for a US-style mailing address.
 // Return null if none is found.
 var findAddress = function() {
@@ skipping 28 matching lines @@
       var trim = /\s{2,}/g;
       return match[0].replace(trim, " ");
     } else {
       console.log("bad initial match: " + found.textContent);
       console.log("no match in: " + text);
     }
   }
   return null;
 }