Use multiple shared memory buffers cyclically for audio capture.

media/audio/audio_input_device.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.
 
 // Low-latency audio capturing class utilizing audio input stream provided
 // by a server (browser) process by use of an IPC interface.
 //
 // Relationship of classes:
 //
 //  AudioInputController                 AudioInputDevice
@@ skipping 85 matching lines @@
                           CaptureEventHandler* event_handler) OVERRIDE;
   virtual void Start() OVERRIDE;
   virtual void Stop() OVERRIDE;
   virtual void SetVolume(double volume) OVERRIDE;
   virtual void SetDevice(int session_id) OVERRIDE;
   virtual void SetAutomaticGainControl(bool enabled) OVERRIDE;
 
  protected:
   // Methods called on IO thread ----------------------------------------------
   // AudioInputIPCDelegate implementation.
-  virtual void OnStreamCreated(base::SharedMemoryHandle handle,
-                               base::SyncSocket::Handle socket_handle,
-                               int length) OVERRIDE;
+  virtual void OnStreamCreated(base::SyncSocket::Handle socket_handle,
+                               int total_handles) OVERRIDE;
+  virtual void OnSharedMemoryCreated(base::SharedMemoryHandle handle,
+                                     int length,
+                                     int index) OVERRIDE;
   virtual void OnVolume(double volume) OVERRIDE;
   virtual void OnStateChanged(
       AudioInputIPCDelegate::State state) OVERRIDE;
   virtual void OnDeviceReady(const std::string& device_id) OVERRIDE;
   virtual void OnIPCClosed() OVERRIDE;
 
   friend class base::RefCountedThreadSafe<AudioInputDevice>;
   virtual ~AudioInputDevice();
 
  private:
@@ skipping 11 matching lines @@
   // MessageLoop::DestructionObserver implementation for the IO loop.
   // If the IO loop dies before we do, we shut down the audio thread from here.
   virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
 
   AudioParameters audio_parameters_;
 
   CaptureCallback* callback_;
   CaptureEventHandler* event_handler_;
 
   AudioInputIPC* ipc_;
+  base::SyncSocket::Handle socket_handle_;
+  AudioDeviceThread::Callback::SharedMemoryHandleVector shared_memory_handles_;
+  int received_shared_memory_count_;
 
   // Our stream ID on the message filter. Only modified on the IO thread.
   int stream_id_;
 
   // The media session ID used to identify which input device to be started.
   // Only modified on the IO thread.
   int session_id_;
 
   // State variable used to indicate it is waiting for a OnDeviceReady()
   // callback. Only modified on the IO thread.
@@ skipping 11 matching lines @@
   base::Lock audio_thread_lock_;
   AudioDeviceThread audio_thread_;
   scoped_ptr<AudioInputDevice::AudioThreadCallback> audio_callback_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioInputDevice);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_INPUT_DEVICE_H_