Clean up removeContentScripts in web_view_internal.json.

extensions/common/api/web_view_internal.json

 // Copyright 2014 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": "webViewInternal",
     "description": "none",
     "compiler_options": {
       "implemented_in": "extensions/browser/api/guest_view/web_view/web_view_internal_api.h"
@@ skipping 260 matching lines @@
           {
             "type": "array",
             "name": "scriptNameList",
             "items": {
               "type": "string",
               "minimum": 0,
               "description": "The name of a content script that will be removed."
             },
             "optional": true,
             "description": "A list of names of content scripts that will be removed. If the list is empty, all the content scripts added to the <webview> page will be removed."
-          },
-          {
-            "type": "function",
-            "name": "callback",
-            "optional": true,
-            "description": "Called when all the content scripts has been removed.",
-            "parameters": []
           }
         ]
       },
       {
         "name": "setZoom",
         "type": "function",
         "parameters": [
           {
             "type": "integer",
             "name": "instanceId",
@@ skipping 399 matching lines @@
             "type": "function",
             "description": "Called when deletion has completed.",
             "optional": true,
             "parameters": []
           }
         ]
       }
     ]
   }
 ]