Lazily load extension API schemas

chrome/common/extensions/api/web_request_internal.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": "webRequestInternal",
-    "dependencies": ["webRequest"],
     "nodoc": true,
     "internal": true,
     "functions": [
       {
         "name": "addEventListener",
         "type": "function",
         "description": "Used internally to implement the special form of addListener for the webRequest events.",
         "parameters": [
           {"type": "function", "name": "callback"},
           {
@@ skipping 26 matching lines @@
           {
             "$ref": "webRequest.BlockingResponse",
             "optional": true,
             "name": "response"
           }
         ]
       }
     ]
   }
 ]