PPAPI: Make blocking completion callbacks work.

ppapi/proxy/ppb_network_monitor_private_proxy.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_PROXY_PPB_NETWORK_MONITOR_PRIVATE_PROXY_H_
 #define PPAPI_PROXY_PPB_NETWORK_MONITOR_PRIVATE_PROXY_H_
 
 #include <list>
 
 #include "base/observer_list_threadsafe.h"
@@ skipping 29 matching lines @@
   friend class NetworkMonitor;
 
   // IPC message handler for the messages received from the browser.
   void OnPluginMsgNetworkList(uint32 plugin_dispatcher_id,
                               const ppapi::NetworkList& list);
 
   // Called by NetworkMonitor destructor.
   void OnNetworkMonitorDeleted(NetworkMonitor* monitor,
                                PP_Instance instance);
 
+  // We use ObserverListThreadSafe because we want to send notifications to the
+  // same thread that created the NetworkMonitor.
   scoped_refptr<ObserverListThreadSafe<NetworkMonitor> > monitors_;
 
   int monitors_count_;
   scoped_refptr<NetworkListStorage> current_list_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_NetworkMonitor_Private_Proxy);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_PPB_NETWORK_MONITOR_PRIVATE_PROXY_H_