Implement two new policies to control muting the audio I/O.

chrome/browser/chromeos/audio/audio_handler.h

 // Copyright (c) 2012 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_AUDIO_HANDLER_H_
 #define CHROME_BROWSER_CHROMEOS_AUDIO_AUDIO_HANDLER_H_
 
 #include "base/basictypes.h"
 #include "base/observer_list.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/thread.h"
+#include "chrome/browser/api/prefs/pref_change_registrar.h"
+#include "content/public/browser/notification_details.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/notification_source.h"
 
 template <typename T> struct DefaultSingletonTraits;
 
+class PrefChangeRegistrar;
 class PrefService;
 
 namespace chromeos {
 
 class AudioMixer;
 
-class AudioHandler {
+class AudioHandler : content::NotificationObserver {
  public:
   class VolumeObserver {
    public:
     virtual void OnVolumeChanged() = 0;
     virtual void OnMuteToggled() = 0;
    protected:
     VolumeObserver() {}
     virtual ~VolumeObserver() {}
     DISALLOW_COPY_AND_ASSIGN(VolumeObserver);
   };
 
   static void Initialize();
   static void Shutdown();
 
   // Same as Initialize but using the specified audio mixer.  It takes
   // ownership of |mixer|.
   static void InitializeForTesting(AudioMixer* mixer);
 
   // GetInstance returns NULL if not initialized or if already shutdown.
   static AudioHandler* GetInstance();
 
   // Registers volume and mute preferences.
   static void RegisterPrefs(PrefService* local_state);

[Mattias Nissler (ping if slow), 2012/08/28 12:24:24]

Rename to disambiguate?

[pastarmovj, 2012/08/28 15:11:50]

Done.

+  static void RegisterUserPrefs(PrefService* user_prefs);
+
+  // Initializes the observers for the policy prefs.
+  void InitializePrefObservers(PrefService* user_prefs);
 
   // Gets volume level in our internal 0-100% range, 0 being pure silence.
   double GetVolumePercent();
 
   // Sets volume level from 0-100%.
   void SetVolumePercent(double volume_percent);
 
   // Adjusts volume up (positive percentage) or down (negative percentage).
   void AdjustVolumeByPercent(double adjust_by_percent);
 
   // Is the volume currently muted?
   bool IsMuted();
 
   // Mutes or unmutes all audio.
   void SetMuted(bool do_mute);
 
+  // Is the mic volume currently muted?
+  bool IsMicMuted();
+
+  // Mutes or unmutes all mics.
+  void SetMicMuted(bool do_mute);
+
   void AddVolumeObserver(VolumeObserver* observer);
   void RemoveVolumeObserver(VolumeObserver* observer);
 
+  // Overridden from content::NotificationObserver:
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
  private:
   // Defines the delete on exit Singleton traits we like.  Best to have this
   // and constructor/destructor private as recommended for Singletons.
   friend struct DefaultSingletonTraits<AudioHandler>;
 
   // Takes ownership of |mixer|.
   explicit AudioHandler(AudioMixer* mixer);
   virtual ~AudioHandler();
 
+  // Applies the audio muting policies whenever the user logs in or policy
+  // change notification is received.
+  void ApplyAudioPolicy();
+
   scoped_ptr<AudioMixer> mixer_;
 
   ObserverList<VolumeObserver> volume_observers_;
 
-  PrefService* prefs_;  // not owned
+  PrefService* local_state_;  // not owned
+  PrefService* user_prefs_;
+
+  PrefChangeRegistrar pref_change_registrar_;
+  content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioHandler);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_AUDIO_AUDIO_HANDLER_H_