Disable surprise me automatically if the current wallpaper was set by a third party application.

chrome/common/extensions/api/wallpaper.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":"wallpaper",
     "compiler_options": {
       "implemented_in": "chrome/browser/chromeos/extensions/wallpaper_api.h"
     },
@@ skipping 42 matching lines @@
             {
               "type": "binary",
               "optional": true,
               "name": "thumbnail",
               "description": "The jpeg encoded wallpaper thumbnail. It is generated by resizing the wallpaper to 128x60."
             }
           ]
         }
       ]
     }
-    ]
+   ],
+   "events": [

[bshe, 2015/03/16 14:02:40]

this should go to wallpaper_private.json. Only our built in wallpaper app cares
about the event.

+     {
+       "name": "OnWallpaperChangedBy3rdParty",
+       "type": "function",
+       "description": "This event is sent when the current wallpaper was set by a third party application."
+     }
+   ]
   }
 ]