Add NetworkListObserver utility class.

ppapi/utility/private/network_list_observer_private.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_UTILITY_PRIVATE_NETWORK_LIST_OBSERVER_H_
+#define PPAPI_UTILITY_PRIVATE_NETWORK_LIST_OBSERVER_H_
+
+#include "ppapi/cpp/private/network_monitor_private.h"
+
+namespace pp {
+
+class NetworkListPrivate;
+
+/// <code>NetworkListObserver</code> is a wrapper for
+/// <code>pp::NetworkMonitorPrivate</code> that makes it easier to
+/// handle network list update notifications. A child class must
+/// implement the <code>OnNetworkListChanged()</code> method. That
+/// method will be called once after the object is created and then
+/// every time network configuration changes.
+class NetworkListObserverPrivate {
+ public:
+  explicit NetworkListObserverPrivate(const InstanceHandle& instance);
+  virtual ~NetworkListObserverPrivate();
+
+ protected:
+  /// Called once after this object is created and later every time
+  /// network configuration changes. Child classes must implement this
+  /// method.
+  ///
+  /// @param[in] list The current list of network interfaces.
+  virtual void OnNetworkListChanged(const NetworkListPrivate& list) = 0;
+
+ private:
+  static void NetworkListCallbackHandler(void* user_data,
+                                         PP_Resource list_resource);
+
+  NetworkMonitorPrivate monitor_;
+};
+
+}  // namespace pp
+
+#endif  // PPAPI_UTILITY_PRIVATE_NETWORK_LIST_OBSERVER_H_