Disable the new window context menu option in the bookmarks extension for Windows 8 metro mode.

chrome/common/extensions/api/experimental_bookmark_manager.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.bookmarkManager",
     "nodoc": true,
     "dependencies": [ "bookmarks" ],
     "types": [
@@ skipping 191 matching lines @@
       {
         "name": "canEdit",
         "type": "function",
         "description": "Whether bookmarks can be modified",
         "nodoc": "true",
         "parameters": [
           {"type": "function", "name": "callback", "parameters": [
             {"name": "result", "type": "boolean"}
           ]}
         ]
+      },
+      {
+        "name": "canOpenNewWindows",
+        "type": "function",
+        "description": "Whether bookmarks can be opened in new windows",
+        "nodoc": "true",
+        "parameters": [
+          {"type": "function", "name": "callback", "parameters": [
+            {"name": "result", "type": "boolean"}
+          ]}
+        ]
       }
     ],
     "events": [
       {
         "name": "onDragEnter",
         "type": "function",
         "description": "Fired when dragging bookmarks over the document",
         "parameters": [
           {"name": "bookmarkNodeData", "$ref": "BookmarkNodeData"}
         ]
@@ skipping 10 matching lines @@
         "name": "onDrop",
         "type": "function",
         "description": "Fired when the user drops bookmarks on the document",
         "parameters": [
           {"name": "bookmarkNodeData", "$ref": "BookmarkNodeData"}
         ]
       }
     ]
   }
 ]