Remove .html extension from links

chrome/common/extensions/api/extension.json

 // 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.
 
 [
   {
     "namespace": "extension",
-    "description": "The <code>chrome.extension</code> API has utilities that can be used by any extension page. It includes support for exchanging messages between an extension and its content scripts or between extensions, as described in detail in <a href='messaging.html'>Message Passing</a>.",
+    "description": "The <code>chrome.extension</code> API has utilities that can be used by any extension page. It includes support for exchanging messages between an extension and its content scripts or between extensions, as described in detail in <a href='messaging'>Message Passing</a>.",
     "compiler_options": {
       "implemented_in": "chrome/browser/extensions/api/module/module.h"
     },
     "properties": {
       "lastError": {
         "type": "object",
         "optional": true,
         "description": "Set for the lifetime of a callback if an ansychronous extension api has resulted in an error. If no error has occured lastError will be <var>undefined</var>.",
         "properties": {
           "message": { "type": "string", "description": "Description of the error that has taken place." }
@@ skipping 190 matching lines @@
         "description": "Fired when a request is sent from another extension.",
         "parameters": [
           {"name": "request", "type": "any", "optional": true, "description": "The request sent by the calling script."},
           {"name": "sender", "$ref": "runtime.MessageSender" },
           {"name": "sendResponse", "type": "function", "description": "Function to call when you have a response. The argument should be any JSON-ifiable object, or undefined if there is no response." }
         ]
       }
     ]
   }
 ]