Added the "unmodifiable" property to chrome.bookmarks.BookmarkTreeNode.

chrome/common/extensions/api/bookmarks.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": "bookmarks",
     "description": "Use the <code>chrome.bookmarks</code> API to create, organize, and otherwise manipulate bookmarks. Also see <a href='override'>Override Pages</a>, which you can use to create a custom Bookmark Manager page.",
     "properties": {
       "MAX_WRITE_OPERATIONS_PER_HOUR": {
@@ skipping 39 matching lines @@
           "dateAdded": {
             "type": "number",
             "optional": true,
             "description": "When this node was created, in milliseconds since the epoch (<code>new Date(dateAdded)</code>)."
           },
           "dateGroupModified": {
             "type": "number",
             "optional": true,
             "description": "When the contents of this folder last changed, in milliseconds since the epoch."
           },
+          "unmodifiable": {
+            "type": "string",
+            "enum": ["managed"],
+            "optional": true,
+            "description": "Indicates the reason why this node is unmodifiable. The <var>managed</var> value indicates that this node was configured by the system administrator. Omitted if the node can be modified by the user and the extension (default)."
+          },
           "children": {
             "type": "array",
             "optional": true,
             "items": { "$ref": "BookmarkTreeNode" },
             "description": "An ordered list of children of this node."
           }
         }
       },
       {
         "id": "CreateDetails",
@@ skipping 467 matching lines @@
       },
       {
         "name": "onImportEnded",
         "type": "function",
         "description": "Fired when a bookmark import session is ended.",
         "parameters": []
       }
     ]
   }
 ]