Refactor PPB_NetworkMonitor_Private interface to use CompletionCallback.

ppapi/thunk/ppb_network_monitor_private_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 PPAPI_THUNK_PPB_NETWORK_MONITOR_PRIVATE_API_H_
 #define PPAPI_THUNK_PPB_NETWORK_MONITOR_PRIVATE_API_H_
 
 #include "ppapi/c/private/ppb_network_monitor_private.h"
 #include "ppapi/thunk/ppapi_thunk_export.h"
 
 namespace ppapi {
+
+class TrackedCallback;
+
 namespace thunk {
 
 class PPAPI_THUNK_EXPORT PPB_NetworkMonitor_Private_API {
  public:
   virtual ~PPB_NetworkMonitor_Private_API() {}
+
+  virtual int32_t UpdateNetworkList(
+        PP_Resource* network_list,
+        scoped_refptr<TrackedCallback> callback) = 0;
 };
 
 }  // namespace thunk
 }  // namespace ppapi
 
 #endif  // PPAPI_THUNK_PPB_NETWORK_MONITOR_PRIVATE_API_H_