Fix most of the downloads api in incognito profiles

chrome/common/extensions/api/experimental_downloads.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": "experimental.downloads",
     "events": [
       {
         "name": "onCreated",
@@ skipping 124 matching lines @@
             "description": "An identifier that is persistent across browser sessions."
           },
           "url": {
             "type": "string",
             "description": "absolute URL"
           },
           "filename": {
             "type": "string",
             "description": "absolute local path"
           },
+          "incognito": {
+            "type": "boolean",
+            "description": "False if this download is recorded in the history, true if it is not recorded.",
+            "optional": true
+          },
           "danger": {
             "$ref": "DownloadDangerType",
             "description": "Indication of whether this download is thought to be safe or known to be suspicious.",
             "optional": true
           },
           "dangerAccepted": {
             "type": "boolean",
             "description": "true if the user has accepted the download's danger.",
             "optional": true
           },
@@ skipping 497 matching lines @@
                 "type": "string",
                 "description": "A URL to an image that represents the download. If a file icon cannot be determined, chrome.extension.lastError will contain an error message."
               }
             ]
           }
         ]
       }
     ]
   }
 ]