make pulseaudio available for all posix platforms because it's not linux only

media/audio/linux/pulse_output.h

-// Copyright (c) 2011 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 audio output stream based on the PulseAudio asynchronous API.
-//
-// If the stream is successfully opened, Close() must be called before the
-// stream is deleted as Close() is responsible for ensuring resource cleanup
-// occurs.
-//
-// This object is designed so that all AudioOutputStream methods will be called
-// on the same thread that created the object.
-//
-// WARNING: This object blocks on internal PulseAudio calls in Open() while
-// waiting for PulseAudio's context structure to be ready.  It also blocks in
-// inside PulseAudio in Start() and repeated during playback, waiting for
-// PulseAudio write callbacks to occur.
-
-#ifndef MEDIA_AUDIO_LINUX_PULSE_OUTPUT_H_
-#define MEDIA_AUDIO_LINUX_PULSE_OUTPUT_H_
-
-#include <pulse/pulseaudio.h>
-
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
-#include "base/task.h"
-#include "media/audio/audio_io.h"
-#include "media/base/channel_layout.h"
-
-namespace media {
-class SeekableBuffer;
-}
-
-class AudioManagerLinux;
-struct AudioParameters;
-class MessageLoop;
-
-class PulseAudioOutputStream : public AudioOutputStream {
- public:
-  PulseAudioOutputStream(const AudioParameters& params,
-                         AudioManagerLinux* manager,
-                         MessageLoop* message_loop);
-
-  virtual ~PulseAudioOutputStream();
-
-  // Implementation of AudioOutputStream.
-  virtual bool Open();
-  virtual void Close();
-  virtual void Start(AudioSourceCallback* callback);
-  virtual void Stop();
-  virtual void SetVolume(double volume);
-  virtual void GetVolume(double* volume);
-
- private:
-  // PulseAudio Callbacks.
-  static void ContextStateCallback(pa_context* context, void* state_addr);
-  static void WriteRequestCallback(pa_stream* playback_handle, size_t length,
-                                   void* stream_addr);
-
-  // Iterate the PulseAudio mainloop to get write requests.
-  void WaitForWriteRequest();
-
-  // Get another packet from the data source and write it to the client buffer.
-  bool BufferPacketFromSource();
-
-  // Fulfill a write request from the write request callback.  If the write
-  // can't be finished a first, post a new attempt to the message loop.
-  void FulfillWriteRequest(size_t requested_bytes);
-
-  // Write data from the client buffer to the PulseAudio stream.
-  void WriteToStream(size_t bytes_to_write, size_t* bytes_written);
-
-  // API for Proxying calls to the AudioSourceCallback provided during Start().
-  uint32 RunDataCallback(uint8* dest, uint32 max_size,
-                         AudioBuffersState buffers_state);
-
-  // Close() helper function to free internal structs.
-  void Reset();
-
-  // Configuration constants from the constructor.  Referencable by all threads
-  // since they are constants.
-  const ChannelLayout channel_layout_;
-  const uint32 channel_count_;
-  const pa_sample_format_t sample_format_;
-  const uint32 sample_rate_;
-  const uint32 bytes_per_frame_;
-
-  // Audio manager that created us.  Used to report that we've closed.
-  AudioManagerLinux* manager_;
-
-  // PulseAudio API structs.
-  pa_context* pa_context_;
-  pa_mainloop* pa_mainloop_;
-
-  // Handle to the actual PulseAudio playback stream.
-  pa_stream* playback_handle_;
-
-  // Device configuration data.  Populated after Open() completes.
-  uint32 packet_size_;
-  uint32 frames_per_packet_;
-
-  // Client side audio buffer feeding pulse audio's server side buffer.
-  scoped_ptr<media::SeekableBuffer> client_buffer_;
-
-  // Float representation of volume from 0.0 to 1.0.
-  float volume_;
-
-  // Flag indicating the code should stop reading from the data source or
-  // writing to the PulseAudio server.  This is set because the device has
-  // entered an unrecoverable error state, or the Close() has executed.
-  bool stream_stopped_;
-
-  // Whether or not PulseAudio has called the WriteCallback for the most recent
-  // set of pa_mainloop iterations.
-  bool write_callback_handled_;
-
-  // Message loop used to post WaitForWriteTasks.  Used to prevent blocking on
-  // the audio thread while waiting for PulseAudio write callbacks.
-  MessageLoop* message_loop_;
-
-  // Allows us to run tasks on the PulseAudioOutputStream instance which are
-  // bound by its lifetime.
-  base::WeakPtrFactory<PulseAudioOutputStream> weak_factory_;
-
-  // Callback to audio data source.
-  AudioSourceCallback* source_callback_;
-
-  DISALLOW_COPY_AND_ASSIGN(PulseAudioOutputStream);
-};
-
-#endif  // MEDIA_AUDIO_LINUX_PULSE_OUTPUT_H_