Implement audio recording for Linux via ALSA.

media/audio/linux/alsa_output.h

 // Copyright (c) 2010 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.
 //
 // Creates an output stream based on the ALSA PCM interface.
 //
 // On device write failure, the stream will move itself to an invalid state.
 // No more data will be pulled from the data source, or written to the device.
 // All calls to public API functions will either no-op themselves, or return an
 // error if possible.  Specifically, If the stream is in an error state, Open()
@@ skipping 124 matching lines @@
   // ALSA device.
   void BufferPacket(bool* source_exhausted);
   void WritePacket();
   void WriteTask();
   void ScheduleNextWrite(bool source_exhausted);
 
   // Utility functions for talking with the ALSA API.
   static uint32 FramesToMicros(uint32 frames, uint32 sample_rate);
   static uint32 FramesToMillis(uint32 frames, uint32 sample_rate);
   std::string FindDeviceForChannels(uint32 channels);
-  snd_pcm_t* OpenDevice(const std::string& device_name,
-                        uint32 channels,
-                        uint32 latency);
-  bool CloseDevice(snd_pcm_t* handle);
   snd_pcm_sframes_t GetAvailableFrames();
 
   // Attempts to find the best matching linux audio device for the given number
   // of channels.  This function will set |device_name_| and |should_downmix_|.
   snd_pcm_t* AutoSelectDevice(uint32 latency);
 
   // Thread-asserting accessors for member variables.
   AudioManagerLinux* manager();
 
   // Struct holding all mutable the data that must be shared by the
@@ skipping 84 matching lines @@
   MessageLoop* client_thread_loop_;
 
   // The message loop responsible for querying the data source, and writing to
   // the output device.
   MessageLoop* message_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(AlsaPcmOutputStream);
 };
 
 #endif  // MEDIA_AUDIO_LINUX_ALSA_OUTPUT_H_