"platforms" in privacy.json should be "chromeos" not "cros".

chrome/common/extensions/api/privacy.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": "privacy",
     "dependencies": [ "types" ],
     "properties": {
       "network": {
@@ skipping 67 matching lines @@
           },
           "referrersEnabled": {
             "$ref": "types.ChromeSetting",
             "value": ["referrersEnabled", {"type":"boolean"}],
             "description": "If enabled, Chrome sends <code>referer</code> headers with your requests. Yes, the name of this preference doesn't match the misspelled header. No, we're not going to change it. The value of this preference is of type boolean, and the default value is <code>true</code>."
           },
           "protectedContentEnabled": {
             "$ref": "types.ChromeSetting",
             "value": ["protectedContentEnabled", {"type":"boolean"}],
             "description": "<strong>Available on ChromeOS only</strong>: If enabled, Chrome provides a unique ID to plugins in order to run protected content. The value of this preference is of type boolean, and the default value is <code>true</code>.",
-            "platforms": ["cros", "cros touch"]
+            "platforms": ["chromeos", "chromeos touch"]
           }
         }
       }
     }
   }
 ]