Use multiple shared memory buffers cyclically for audio capture.

media/audio/audio_input_device.h

Index: media/audio/audio_input_device.h
===================================================================
--- media/audio/audio_input_device.h	(revision 185810)
+++ media/audio/audio_input_device.h	(working copy)
@@ -103,9 +103,11 @@
  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;
@@ -137,6 +139,9 @@
   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_;