Move API functions registrations out of ExtensionFunctionRegistry.

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"],
     "nodoc": "true",
     "functions": [
       {
         "name": "getStrings",
         "type": "function",
         "description": "Gets translated strings.",
         "nodoc": "true",
         "parameters": [
           {
             "type": "function",
@@ skipping 159 matching lines @@
                 "name": "results",
                 "items": {"type": "string"}
               }
             ]
           }
         ]
       }
     ]
   }
 ]