Handle audio node stable device ID change

chromeos/audio/audio_devices_pref_handler_impl.h

 // Copyright (c) 2013 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 CHROMEOS_AUDIO_AUDIO_DEVICES_PREF_HANDLER_IMPL_H_
 #define CHROMEOS_AUDIO_AUDIO_DEVICES_PREF_HANDLER_IMPL_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 55 matching lines @@
   void LoadDevicesVolumePref();
   void SaveDevicesVolumePref();
 
   // Load and save methods for the active state for all devices.
   void LoadDevicesStatePref();
   void SaveDevicesStatePref();
 
   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();
 
   std::unique_ptr<base::DictionaryValue> device_mute_settings_;
   std::unique_ptr<base::DictionaryValue> device_volume_settings_;
   std::unique_ptr<base::DictionaryValue> device_state_settings_;
 
   PrefService* local_state_;  // not owned
 
   PrefChangeRegistrar pref_change_registrar_;
   base::ObserverList<AudioPrefObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioDevicesPrefHandlerImpl);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_AUDIO_AUDIO_DEVICES_PREF_HANDLER_IMPL_H_