Save/Restore ALSA volume/mute

chrome/browser/chromeos/audio_mixer_alsa.h

 // Copyright (c) 2010 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 CHROME_BROWSER_CHROMEOS_AUDIO_MIXER_ALSA_H_
 #define CHROME_BROWSER_CHROMEOS_AUDIO_MIXER_ALSA_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/lock.h"
 #include "base/scoped_ptr.h"
 #include "base/threading/thread.h"
 #include "chrome/browser/chromeos/audio_mixer.h"
+#include "chrome/browser/prefs/pref_member.h"
 
 struct _snd_mixer_elem;
 struct _snd_mixer;
 
 namespace chromeos {
 
 class AudioMixerAlsa : public AudioMixer {
  public:
   AudioMixerAlsa();
   virtual ~AudioMixerAlsa();
 
   // Implementation of AudioMixer
   virtual void Init(InitDoneCallback* callback);
   virtual bool InitSync();
   virtual double GetVolumeDb() const;
   virtual bool GetVolumeLimits(double* vol_min, double* vol_max);
   virtual void SetVolumeDb(double vol_db);
   virtual bool IsMute() const;
   virtual void SetMute(bool mute);
   virtual State GetState() const;
 
+  // Registers volume and mute in preferences
+  static void RegisterPrefs(PrefService* local_state);
+
  private:
   // Called to do initialization in background from worker thread.
   void DoInit(InitDoneCallback* callback);
 
-  // Helper function to just get our message loop thread going.
+  // Helper functions to get our message loop thread and prefs initialized.
   bool InitThread();
+  void InitPrefs();
 
   // Try to connect to the ALSA mixer through their simple controls interface,
   // and cache mixer handle and mixer elements we'll be using.
   bool InitializeAlsaMixer();
   void FreeAlsaMixer();
+  void DoSetVolumeMute(double pref_volume, int pref_mute);
+
+  // Access to PrefMember variables must be done on UI thread.
+  void RestoreVolumeMuteOnUIThread();
 
   // All these internal volume commands must be called with the lock held.
   double DoGetVolumeDb_Locked() const;
   void DoSetVolumeDb_Locked(double vol_db);
 
   _snd_mixer_elem* FindElementWithName_Locked(_snd_mixer* handle,
                                               const char* element_name) const;
 
   bool GetElementVolume_Locked(_snd_mixer_elem* elem,
                                double* current_vol) const;
@@ skipping 23 matching lines @@
   double save_volume_;
 
   mutable Lock mixer_state_lock_;
   mutable State mixer_state_;
 
   // Cached contexts for use in ALSA calls.
   _snd_mixer* alsa_mixer_;
   _snd_mixer_elem* elem_master_;
   _snd_mixer_elem* elem_pcm_;
 
+  IntegerPrefMember mute_pref_;
+  RealPrefMember volume_pref_;
+
   scoped_ptr<base::Thread> thread_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioMixerAlsa);
 };
 
 }  // namespace chromeos
 
 DISABLE_RUNNABLE_METHOD_REFCOUNT(chromeos::AudioMixerAlsa);
 
 #endif  // CHROME_BROWSER_CHROMEOS_AUDIO_MIXER_ALSA_H_