Fix wallpaper picker crash in debug build

chrome/common/extensions/api/wallpaper_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":"wallpaperPrivate",
     "compiler_options": {
       "implemented_in": "chrome/browser/chromeos/extensions/wallpaper_private_api.h"
     },
     "platforms": ["chromeos"],
     "description": "none",
     "types": [
       {
         "id": "WallpaperLayout",
         "type": "string",
         "enum": [ "STRETCH", "CENTER", "CENTER_CROPPED" ]
       }
     ],
     "functions": [
       {
         "name": "getStrings",
         "type": "function",
-        "description": "Gets translated strings.",
+        "description": "Gets translated strings and initialization data.",
         "nodoc": "true",
         "parameters": [
           {
             "type": "function",
             "name": "callback",
             "parameters": [
               {
                 "name": "result",
                 "type": "object",
-                "additionalProperties": {"type": "string"}
+                "additionalProperties": {"type": "any"}
               }
             ]
           }
         ]
       },
       {
         "name": "setWallpaperIfExists",
         "type": "function",
         "description": "Sets wallpaper if it exists in the local file system with specified layout",
         "nodoc": "true",
@@ skipping 189 matching lines @@
                 "name": "results",
                 "items": {"type": "string"}
               }
             ]
           }
         ]
       }
     ]
   }
 ]