Handle audio node stable device ID change

chromeos/audio/audio_devices_pref_handler_impl.h

Index: chromeos/audio/audio_devices_pref_handler_impl.h
diff --git a/chromeos/audio/audio_devices_pref_handler_impl.h b/chromeos/audio/audio_devices_pref_handler_impl.h
index ec4f6e11766de19fc31f03025d97b86ace5781a2..eabd2250ed8fe03d2ec94b3bbbc890e5307369b3 100644
--- a/chromeos/audio/audio_devices_pref_handler_impl.h
+++ b/chromeos/audio/audio_devices_pref_handler_impl.h
@@ -73,12 +73,29 @@ class CHROMEOS_EXPORT AudioDevicesPrefHandlerImpl
   double GetVolumeGainPrefValue(const AudioDevice& device);
   double GetDeviceDefaultOutputVolume(const AudioDevice& device);
 
-  // Methods to migrate the mute and volume settings for a device from the
-  // previous global pref value to the new per device pref value for the
-  // current active device. If a previous global setting doesn't exist, we'll
-  // use default values of mute = off and volume = 75%.
-  void MigrateDeviceMuteSettings(const std::string& active_device);
-  void MigrateDeviceVolumeSettings(const std::string& active_device);
+  // Migrates devices state pref for an audio device. Device settings are
+  // saved under device stable device ID - this method migrates device state
+  // for a device that is saved under key derived from v1 stable device ID to
+  // |device_key|. Note that |device_key| should be the key derived from
+  // |device|'s v2 stable device ID.
+  bool MigrateDevicesStatePref(const std::string& device_key,
+                               const AudioDevice& device);
+
+  // Methods to migrate the mute and volume settings for an audio device.
+  // Migration is done in the folowing way:
+  //   1. If there is a setting for the device under |device_key|, do nothing.
+  //      (Note that |device_key| is expected to be the key derived from
+  //       |device's| v2 stable device ID).
+  //   2. If there is a setting for the device under the key derived from
+  //      |device|'s v1 stable device ID, move the value to |device_key|.
+  //   3. If a previous global pref value exists, move it to the per device
+  //      setting (under |device_key|).
+  //   4. If a previous global setting is not set, use default values of
+  //      mute = off and volume = 75%.
+  void MigrateDeviceMuteSettings(const std::string& device_key,
+                                 const AudioDevice& device);
+  void MigrateDeviceVolumeGainSettings(const std::string& device_key,
+                                       const AudioDevice& device);
 
   // Notifies the AudioPrefObserver for audio policy pref changes.
   void NotifyAudioPolicyChange();