Store audio device's active state in preference

chromeos/chromeos_pref_names.cc

 // Copyright 2014 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.
 
 #include "chromeos/chromeos_pref_names.h"
 
 namespace chromeos {
 namespace prefs {
 
 // A dictionary pref to hold the mute setting for all the currently known
@@ skipping 15 matching lines @@
 // A pref holding the value of the policy used to disable playing audio on
 // ChromeOS devices. This pref overrides |kAudioMute| but does not overwrite
 // it, therefore when the policy is lifted the original mute state is restored.
 const char kAudioOutputAllowed[] = "hardware.audio_output_enabled";
 
 // A double pref storing the user-requested volume. This setting is here only
 // for migration purposes now. It is being replaced by the
 // |kAudioDevicesVolumePercent| setting.
 const char kAudioVolumePercent[] = "settings.audio.volume_percent";
 
+// A dictionary pref that maps stable device id string to |AudioDeviceState|.
+// Different state values indicate whether or not a device has been selected
+// as the active one for audio I/O, or it's a new plugged device.
+const char kAudioDevicesState[] = "settings.audio.device_state";
+
 }  // namespace prefs
 }  // namespace chromeos