Output device enumeration for Alsa, plus unit test.

media/audio/linux/audio_manager_linux.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.
 
 #ifndef MEDIA_AUDIO_LINUX_AUDIO_MANAGER_LINUX_H_
 #define MEDIA_AUDIO_LINUX_AUDIO_MANAGER_LINUX_H_
 
 #include <string>
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/thread.h"
 #include "media/audio/audio_manager_base.h"
 
 namespace media {
 
 class AlsaWrapper;
 
 class MEDIA_EXPORT AudioManagerLinux : public AudioManagerBase {
  public:
   AudioManagerLinux();
 
   static void ShowLinuxAudioInputSettings();
 
   // Implementation of AudioManager.
   virtual bool HasAudioOutputDevices() OVERRIDE;
   virtual bool HasAudioInputDevices() OVERRIDE;
   virtual void ShowAudioInputSettings() OVERRIDE;
   virtual void GetAudioInputDeviceNames(media::AudioDeviceNames* device_names)
       OVERRIDE;
+  virtual void GetAudioOutputDeviceNames(media::AudioDeviceNames* device_names)
+      OVERRIDE;
   virtual AudioParameters GetInputStreamParameters(
       const std::string& device_id) OVERRIDE;
 
   // Implementation of AudioManagerBase.
   virtual AudioOutputStream* MakeLinearOutputStream(
       const AudioParameters& params) OVERRIDE;
   virtual AudioOutputStream* MakeLowLatencyOutputStream(
       const AudioParameters& params,
       const std::string& device_id,
       const std::string& input_device_id) OVERRIDE;
   virtual AudioInputStream* MakeLinearInputStream(
       const AudioParameters& params, const std::string& device_id) OVERRIDE;
   virtual AudioInputStream* MakeLowLatencyInputStream(
       const AudioParameters& params, const std::string& device_id) OVERRIDE;
 
  protected:
   virtual ~AudioManagerLinux();
 
   virtual AudioParameters GetPreferredOutputStreamParameters(
       const std::string& output_device_id,
       const AudioParameters& input_params) OVERRIDE;
 
  private:
   enum StreamType {
     kStreamPlayback = 0,
     kStreamCapture,
   };
 
-  // Gets a list of available ALSA input devices.
-  void GetAlsaAudioInputDevices(media::AudioDeviceNames* device_names);
+  // Gets a list of available ALSA devices.
+  void GetAlsaAudioDevices(StreamType type,
+                           media::AudioDeviceNames* device_names);
 
-  // Gets the ALSA devices' names and ids.
-  void GetAlsaDevicesInfo(void** hint, media::AudioDeviceNames* device_names);
+  // Gets the ALSA devices' names and ids that support streams of the
+  // given type.
+  void GetAlsaDevicesInfo(StreamType type,
+                          void** hint,
+                          media::AudioDeviceNames* device_names);
 
   // Checks if the specific ALSA device is available.
-  bool IsAlsaDeviceAvailable(const char* device_name);
+  static bool IsAlsaDeviceAvailable(StreamType type,
+                                    const char* device_name);
+
+  static const char* UnwantedDeviceTypeWhenEnumerating(
+      StreamType wanted_type);
 
   // Returns true if a device is present for the given stream type.
   bool HasAnyAlsaAudioDevice(StreamType stream);
 
   // Called by MakeLinearOutputStream and MakeLowLatencyOutputStream.
   AudioOutputStream* MakeOutputStream(const AudioParameters& params);
 
   // Called by MakeLinearInputStream and MakeLowLatencyInputStream.
   AudioInputStream* MakeInputStream(const AudioParameters& params,
                                     const std::string& device_id);
 
   scoped_ptr<AlsaWrapper> wrapper_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerLinux);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_LINUX_AUDIO_MANAGER_LINUX_H_