[Extensions API] Remove inline enums

chrome/common/extensions/api/system_private.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": "systemPrivate",
     "description": "none",
     "types": [
       {
+        "id": "UpdateStatusState",
+        "type": "string",
+        "enum": ["NotAvailable", "Updating", "NeedRestart"],
+        "description": "State of system update.  NotAvailable when there is no available update or the update system is in error state, Updating when a system update is in progress, NeedRestart when a system update is finished and restart is needed."
+      },
+      {
+        "id": "GetIncognitoModeAvailabilityValue",
+        "type": "string",
+        "enum": ["enabled", "disabled", "forced"],
+        "description": "Exposes whether the incognito mode is available to windows. One of 'enabled', 'disabled' (user cannot browse pages in Incognito mode), 'forced' (all pages/sessions are forced into Incognito mode)."
+      },
+      {
         "id": "UpdateStatus",
         "type": "object",
         "description": "Information about the system update.",
         "properties": {
           "state": {
-            "type": "string",
-            "enum": ["NotAvailable", "Updating", "NeedRestart"],
-            "description": "State of system update.  NotAvailable when there is no available update or the update system is in error state, Updating when a system update is in progress, NeedRestart when a system update is finished and restart is needed."
+            "$ref": "UpdateStatusState",
+            "description": "State of system update."
           },
           "downloadProgress": {
             "type": "number",
             "description": "Value between 0 and 1 describing the progress of system update download.  This value will be set to 0 when |state| is NotAvailable, 1 when NeedRestart."
           }
         }
       },
       {
         "id": "VolumeInfo",
         "type": "object",
@@ skipping 25 matching lines @@
         "type": "function",
         "description": "Returns whether the incognito mode is enabled, disabled or forced",
         "parameters": [
           {
             "name": "callback",
             "type": "function",
             "description": "Called with the result.",
             "parameters": [
               {
                 "name": "value",
-                "type": "string",
-                "enum": ["enabled", "disabled", "forced"],
-                "description": "Exposes whether the incognito mode is available to windows. One of 'enabled', 'disabled' (user cannot browse pages in Incognito mode), 'forced' (all pages/sessions are forced into Incognito mode)."
+                "$ref": "GetIncognitoModeAvailabilityValue"
               }
             ]
           }
         ]
       },
       {
         "name": "getUpdateStatus",
         "type": "function",
         "description": "Gets information about the system update.",
         "parameters": [
@@ skipping 62 matching lines @@
       },
       {
         "name": "onWokeUp",
         "type": "function",
         "description": "Fired when the device wakes up from sleep.",
         "parameters": []
       }
     ]
   }
 ]