The first step to add device selection to linux.

media/audio/linux/audio_manager_linux.h

Index: media/audio/linux/audio_manager_linux.h
===================================================================
--- media/audio/linux/audio_manager_linux.h	(revision 106080)
+++ media/audio/linux/audio_manager_linux.h	(working copy)
@@ -42,9 +42,23 @@
   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_;