The first step to add device selection to linux.

media/audio/linux/audio_manager_linux.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.
 
 #ifndef MEDIA_AUDIO_LINUX_AUDIO_MANAGER_LINUX_H_
 #define MEDIA_AUDIO_LINUX_AUDIO_MANAGER_LINUX_H_
 
 #include <set>
 
 #include "base/compiler_specific.h"
@@ skipping 24 matching lines @@
 
   virtual void MuteAll() OVERRIDE;
   virtual void UnMuteAll() OVERRIDE;
 
   virtual void ReleaseOutputStream(AudioOutputStream* stream);
 
  protected:
   virtual ~AudioManagerLinux();
 
  private:
-  // Helper method to query if there is any valid input device
-  bool HasAnyValidAudioInputDevice(void** hint);
+  enum StreamType {
+    kStreamPlayback = 0,
+    kStreamCapture,
+  };
+
+  // Gets a list of available ALSA input devices.
+  void GetAlsaAudioInputDevices(media::AudioDeviceNames* device_names);
+
+  // Gets the ALSA devices' names and ids.
+  void GetAlsaDevicesInfo(void** hint, media::AudioDeviceNames* device_names);
+
+  // Checks if the specific ALSA device is available.
+  bool IsAlsaDeviceAvailable(const char* device_name);
+
+  // Returns true if a device is present for the given stream type.
+  bool HasAnyAlsaAudioDevice(StreamType stream);
 
   scoped_ptr<AlsaWrapper> wrapper_;
 
   std::set<AudioOutputStream*> active_streams_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerLinux);
 };
 
 #endif  // MEDIA_AUDIO_LINUX_AUDIO_MANAGER_LINUX_H_