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

chrome/browser/chromeos/audio/audio_handler.cc

Index: chrome/browser/chromeos/audio/audio_handler.cc
diff --git a/chrome/browser/chromeos/audio/audio_handler.cc b/chrome/browser/chromeos/audio/audio_handler.cc
index 76eb60a9af31f2e8584ba5b8b559e42073439018..02d4256d0f10a06b12b3a1f447d95201b84ec7ff 100644
--- a/chrome/browser/chromeos/audio/audio_handler.cc
+++ b/chrome/browser/chromeos/audio/audio_handler.cc
@@ -15,9 +15,13 @@
 #else
 #include "chrome/browser/chromeos/audio/audio_mixer_alsa.h"
 #endif
+#include "chrome/browser/chromeos/login/user_manager.h"

[Mattias Nissler (ping if slow), 2012/08/31 08:06:51]

not longer needed

[pastarmovj, 2012/09/03 09:53:56]

Done.

 #include "chrome/browser/prefs/pref_service.h"
+#include "chrome/browser/profiles/profile.h"

[Mattias Nissler (ping if slow), 2012/08/31 08:06:51]

not needed?

[pastarmovj, 2012/09/03 09:53:56]

Done.

+#include "chrome/common/chrome_notification_types.h"
 #include "chrome/common/pref_names.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/notification_service.h"
 
 using std::max;
 using std::min;
@@ -80,6 +84,14 @@ void AudioHandler::RegisterPrefs(PrefService* local_state) {
                                      kPrefMuteOff,
                                      PrefService::UNSYNCABLE_PREF);
 
+  // Register the prefs backing the audio muting policies.
+  local_state->RegisterBooleanPref(prefs::kAudioOutputAllowed,
+                                  true,

[Daniel Erat, 2012/08/31 14:57:46]

nit: fix indenting

[pastarmovj, 2012/09/03 09:53:56]

Done.

+                                  PrefService::UNSYNCABLE_PREF);
+  local_state->RegisterBooleanPref(prefs::kAudioCaptureAllowed,
+                                  true,

[Daniel Erat, 2012/08/31 14:57:46]

nit: fix indenting

[pastarmovj, 2012/09/03 09:53:56]

Done.

+                                  PrefService::UNSYNCABLE_PREF);
+
   // Register the old decibel-based pref so we can clear it.
   // TODO(derat): Remove this after R20: http://crbug.com/112039
   if (!local_state->FindPreference(prefs::kAudioVolumeDb))
@@ -99,7 +111,7 @@ void AudioHandler::SetVolumePercent(double volume_percent) {
   if (IsMuted() && volume_percent > 0.0)
     SetMuted(false);
   mixer_->SetVolumePercent(volume_percent);
-  prefs_->SetDouble(prefs::kAudioVolumePercent, volume_percent);
+  local_state_->SetDouble(prefs::kAudioVolumePercent, volume_percent);
   FOR_EACH_OBSERVER(VolumeObserver, volume_observers_, OnVolumeChanged());
 }
 
@@ -112,11 +124,23 @@ bool AudioHandler::IsMuted() {
 }
 
 void AudioHandler::SetMuted(bool mute) {
-  mixer_->SetMuted(mute);
-  prefs_->SetInteger(prefs::kAudioMute, mute ? kPrefMuteOn : kPrefMuteOff);
+  if (!mixer_->IsMuteLocked()) {
+    mixer_->SetMuted(mute);
+    local_state_->SetInteger(prefs::kAudioMute,
+                             mute ? kPrefMuteOn : kPrefMuteOff);
+  }
   FOR_EACH_OBSERVER(VolumeObserver, volume_observers_, OnMuteToggled());

[Daniel Erat, 2012/08/31 14:57:46]

should this be inside the 'if' statement?  otherwise, you're notifying the
observers even when nothing changed, no?

[pastarmovj, 2012/09/03 09:53:56]

Done.

 }
 
+bool AudioHandler::IsCaptureMuted() {
+  return mixer_->IsCaptureMuted();
+}
+
+void AudioHandler::SetCaptureMuted(bool mute) {
+  if (!mixer_->IsCaptureMuteLocked())
+    mixer_->SetCaptureMuted(mute);
+}
+
 void AudioHandler::AddVolumeObserver(VolumeObserver* observer) {
   volume_observers_.AddObserver(observer);
 }
@@ -125,11 +149,26 @@ void AudioHandler::RemoveVolumeObserver(VolumeObserver* observer) {
   volume_observers_.RemoveObserver(observer);
 }
 
+void AudioHandler::Observe(int type,
+                           const content::NotificationSource& source,
+                           const content::NotificationDetails& details) {
+  if (type == chrome::NOTIFICATION_PREF_CHANGED) {
+    std::string* pref_name = content::Details<std::string>(details).ptr();
+    if (*pref_name == prefs::kAudioOutputAllowed ||
+        *pref_name == prefs::kAudioCaptureAllowed) {
+      ApplyAudioPolicy();
+    }
+  } else {
+    NOTREACHED() << "Unexpected notification type : " << type;
+  }
+}
+
 AudioHandler::AudioHandler(AudioMixer* mixer)
     : mixer_(mixer),
-      prefs_(g_browser_process->local_state()) {
-  mixer_->SetVolumePercent(prefs_->GetDouble(prefs::kAudioVolumePercent));
-  mixer_->SetMuted(prefs_->GetInteger(prefs::kAudioMute) == kPrefMuteOn);
+      local_state_(g_browser_process->local_state()) {
+  InitializePrefObservers();
+  ApplyAudioPolicy();
+  mixer_->SetVolumePercent(local_state_->GetDouble(prefs::kAudioVolumePercent));
   mixer_->Init();
 }
 
@@ -137,4 +176,29 @@ AudioHandler::~AudioHandler() {
   mixer_.reset();
 };
 
+void AudioHandler::InitializePrefObservers() {
+  pref_change_registrar_.Init(local_state_);
+  pref_change_registrar_.Add(prefs::kAudioOutputAllowed, this);
+  pref_change_registrar_.Add(prefs::kAudioCaptureAllowed, this);
+}
+
+void AudioHandler::ApplyAudioPolicy() {
+  if (local_state_->GetBoolean(prefs::kAudioOutputAllowed)) {
+    mixer_->SetMuteLocked(false);
+    mixer_->SetMuted(
+        local_state_->GetInteger(prefs::kAudioMute) == kPrefMuteOn);
+  } else {
+    mixer_->SetMuted(true);
+    mixer_->SetMuteLocked(true);

[Daniel Erat, 2012/08/31 14:57:46]

might be a bit safer to do something like this:

  mixer_->SetMuteLocked(false);
  if (local_state_->GetBoolean(prefs::kAudioOutputAllowed) {
    mixer_->SetMuted(
        local_state_->GetInteger(prefs::kAudioMute) == kPrefMuteOn);
  } else {
    mixer_->SetMuted(true);
    mixer_->SetMuteLocked(true);
  }

that way, ApplyAudioPolicy() can be called multiple times.  otherwise, i think
you'll hit the NOTREACHED() on the second call if we're locked.

[pastarmovj, 2012/09/03 09:53:56]

Done.

+  }
+  FOR_EACH_OBSERVER(VolumeObserver, volume_observers_, OnMuteToggled());
+  if (local_state_->GetBoolean(prefs::kAudioCaptureAllowed)) {
+    mixer_->SetCaptureMuteLocked(false);
+    mixer_->SetCaptureMuted(false);
+  } else {
+    mixer_->SetCaptureMuted(true);
+    mixer_->SetCaptureMuteLocked(true);
+  }
+}
+
 }  // namespace chromeos