Measure IPC latency for audio...

chrome/renderer/audio_message_filter.h

 // Copyright (c) 2009 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.
 //
 // MessageFilter that handles audio messages and delegates them to audio
 // renderers. Created on render thread, AudioMessageFilter is operated on
 // IO thread (main thread of render process), it intercepts audio messages
 // and process them on IO thread since these messages are time critical.
 
 #ifndef CHROME_RENDERER_AUDIO_MESSAGE_FILTER_H_
@@ skipping 37 matching lines @@
   MessageLoop* message_loop() { return message_loop_; }
 
  private:
   // IPC::ChannelProxy::MessageFilter override. Called on IO thread.
   virtual bool OnMessageReceived(const IPC::Message& message);
   virtual void OnFilterAdded(IPC::Channel* channel);
   virtual void OnFilterRemoved();
   virtual void OnChannelClosing();
 
   // Received when browser process wants more audio packet.
-  void OnRequestPacket(int stream_id);
+  void OnRequestPacket(const IPC::Message& msg, int stream_id);
 
   // Received when browser process has created an audio output stream.
   void OnStreamCreated(int stream_id, base::SharedMemoryHandle handle,
                        int length);
 
   // Received when internal state of browser process' audio output device has
   // changed.
   void OnStreamStateChanged(int stream_id, AudioOutputStream::State state,
                             int info);
 
   // Notification of volume property of an audio output stream.
   void OnStreamVolume(int stream_id, double left, double right);
 
   // A map of stream ids to delegates.
   IDMap<Delegate> delegates_;
 
   IPC::Channel* channel_;
 
   int32 route_id_;
 
   MessageLoop* message_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioMessageFilter);
 };
 
 #endif  // CHROME_RENDERER_AUDIO_MESSAGE_FITLER_H_