Add IDL capability to json_schema_compiler.

chrome/browser/extensions/api/dns/dns_api.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_DNS_DNS_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_DNS_DNS_API_H_
 #pragma once
 
 #include <string>
 
 #include "chrome/browser/extensions/extension_function.h"
 #include "chrome/browser/io_thread.h"
 #include "net/base/address_list.h"
 #include "net/base/capturing_net_log.h"
 #include "net/base/completion_callback.h"
 #include "net/base/host_resolver.h"
 
 class IOThread;
 
 namespace extensions {
 
-extern const char kAddressKey[];
-extern const char kResultCodeKey[];
-
 class DNSResolveFunction : public AsyncExtensionFunction {
  public:
   DNSResolveFunction();
   virtual ~DNSResolveFunction();
 
   virtual bool RunImpl() OVERRIDE;
 
   // See below. Caller retains ownership.
   static void set_host_resolver_for_testing(
       net::HostResolver* host_resolver_for_testing);
@@ skipping 22 matching lines @@
   scoped_ptr<net::AddressList> addresses_;
 
   void OnLookupFinished(int result);
 
   DECLARE_EXTENSION_FUNCTION_NAME("experimental.dns.resolve")
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_DNS_DNS_API_H_