Persist the user's active audio device choice across chromeos session and reboots.

chromeos/audio/audio_devices_pref_handler_stub.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_STUB_H_
 #define CHROMEOS_AUDIO_AUDIO_DEVICES_PREF_HANDLER_STUB_H_
 
 #include <stdint.h>
 
 #include <map>
 
 #include "base/macros.h"
 #include "chromeos/audio/audio_devices_pref_handler.h"
 
 namespace chromeos {
 
 // Stub class for AudioDevicesPrefHandler, used for testing.
 class CHROMEOS_EXPORT AudioDevicesPrefHandlerStub
     : public AudioDevicesPrefHandler {
  public:
+  struct DeviceState {
+    bool active;
+    bool activate_by_user;
+  };
+
   using AudioDeviceMute = std::map<uint64_t, bool>;
   using AudioDeviceVolumeGain = std::map<uint64_t, int>;
-  using AudioDeviceLastState = std::map<uint64_t, AudioDeviceState>;
+  using AudioDeviceStateMap = std::map<uint64_t, DeviceState>;
 
   AudioDevicesPrefHandlerStub();
 
   // AudioDevicesPrefHandler:
   double GetOutputVolumeValue(const AudioDevice* device) override;
   double GetInputGainValue(const AudioDevice* device) override;
   void SetVolumeGainValue(const AudioDevice& device, double value) override;
   bool GetMuteValue(const AudioDevice& device) override;
   void SetMuteValue(const AudioDevice& device, bool mute_on) override;
-  AudioDeviceState GetDeviceState(const AudioDevice& device) override;
-  void SetDeviceState(const AudioDevice& device,
-                      AudioDeviceState state) override;
+  void SetDeviceActive(const AudioDevice& device,
+                       bool active,
+                       bool activate_by_user) override;
+  bool GetDeviceActive(const AudioDevice& device,
+                       bool* active,
+                       bool* activate_by_user) override;
   bool GetAudioOutputAllowedValue() override;
   void AddAudioPrefObserver(AudioPrefObserver* observer) override;
   void RemoveAudioPrefObserver(AudioPrefObserver* observer) override;
 
  protected:
   ~AudioDevicesPrefHandlerStub() override;
 
  private:
   AudioDeviceMute audio_device_mute_map_;
   AudioDeviceVolumeGain audio_device_volume_gain_map_;
-  AudioDeviceLastState audio_device_state_map_;
+  AudioDeviceStateMap audio_device_state_map_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioDevicesPrefHandlerStub);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_AUDIO_AUDIO_DEVICES_PREF_HANDLER_STUB_H_