Move API functions registrations out of ExtensionFunctionRegistry.

chrome/common/extensions/api/echo_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": "echoPrivate",
+    "compiler_options": {
+      "implemented_in": "chrome/browser/chromeos/extensions/echo_private_api.h"
+    },
     "nodoc": true,
     "platforms": ["chromeos"],
     "types": [],
     "functions": [
       {
         "name": "getRegistrationCode",
         "description": "Get the group or coupon code from underlying storage.",
         "type": "function",
         "parameters": [
           {
@@ skipping 10 matching lines @@
                 "type": "string",
                 "description" : "The coupon code."
               }
             ]
           }
         ]
       }
     ]
   }
 ]