Add hook for extension to check sync status.

chrome/common/extensions/api/preferences_private.json

 // Copyright 2013 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": "preferencesPrivate",
     "description": "none",
     "properties": {
       "googleGeolocationAccessEnabled": {

[not at google - send to devlin, 2013/12/18 22:30:37]

add "nocompile": true to this.

[Rune Fevang, 2013/12/19 00:13:43]

Done.

         "$ref": "types.private.ChromeDirectSetting",
         "value": ["googlegeolocationaccess.enabled", {"type":"boolean"}],
         "description": "If enabled, Google services can access the user's location. This preference's value is a boolean, defaulting to <code>false</code>."
       }
-    }
+    },
+    "functions": [
+      {
+        "name": "getSyncCategoriesWithoutPassphrase",
+        "description": "Returns a list of sync categories the user has enabled without using a custom passphrase for encryption",
+        "type": "function",
+        "parameters": [
+          {
+            "name": "callback",
+            "type": "function",
+            "parameters": [
+              {
+                "name": "categories",
+                "type": "array",
+                "items": {"type": "string"}
+              }
+            ]
+          }
+        ]
+      }
+    ]
   }
 ]