Adding `content_security_policy` to a few sample extensions.

chrome/common/extensions/docs/examples/api/devtools/network/chrome-firephp/devtools.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.
+
 function Console() {
 }
 
 Console.Type = {
   LOG: "log",
   DEBUG: "debug",
   INFO: "info",
   WARN: "warn",
   ERROR: "error",
   GROUP: "group",
@@ skipping 161 matching lines @@
   if (!entries.length) {
     Console.warn("ChromeFirePHP suggests that you reload the page to track" +
         " FirePHP messages for all the requests");
   }
   for (var i = 0; i < entries.length; ++i)
     ChromeFirePHP.handleFirePhp_headers(entries[i]);
 
   chrome.experimental.devtools.network.onRequestFinished.addListener(
       ChromeFirePHP.handleFirePhpHeaders.bind(ChromeFirePHP));
 });