Lazily load extension API schemas

chrome/common/extensions/api/browser_action.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": "browserAction",
-    "dependencies": [ "tabs" ],
     "types": [
       {
         "id": "ColorArray",
         "type": "array",
         "items": {
           "type": "integer",
           "minimum": 0,
           "maximum": 255
         },
         "minItems": 4,
@@ skipping 301 matching lines @@
         "parameters": [
           {
             "name": "tab",
             "$ref": "tabs.Tab"
           }
         ]
       }
     ]
   }
 ]