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 87 matching lines @@
   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;
+                               int length,
+                               int total_segments) 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 42 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_