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

chrome/browser/chromeos/audio/audio_mixer_alsa.cc

Index: chrome/browser/chromeos/audio/audio_mixer_alsa.cc
diff --git a/chrome/browser/chromeos/audio/audio_mixer_alsa.cc b/chrome/browser/chromeos/audio/audio_mixer_alsa.cc
index c51cca8554cc0660791fb6a2041afdb495341b57..c4e6cbef95d481fa75347f739a42c6af2389f675 100644
--- a/chrome/browser/chromeos/audio/audio_mixer_alsa.cc
+++ b/chrome/browser/chromeos/audio/audio_mixer_alsa.cc
@@ -41,6 +41,9 @@ const char* const kMasterElementNames[] = {
 };
 const char kPCMElementName[] = "PCM";
 
+const char kMicElementName[] = "Mic";
+const char kFrontMicElementName[] = "Front Mic";
+
 // Default minimum and maximum volume (before we've loaded the actual range from
 // ALSA), in decibels.
 const double kDefaultMinVolumeDb = -90.0;
@@ -76,6 +79,8 @@ AudioMixerAlsa::AudioMixerAlsa()
       initial_volume_percent_(kDefaultVolumePercent),
       alsa_mixer_(NULL),
       pcm_element_(NULL),
+      mic_element_(NULL),
+      front_mic_element_(NULL),
       disconnected_event_(true, false),
       num_connection_attempts_(0) {
 }
@@ -141,12 +146,58 @@ bool AudioMixerAlsa::IsMuted() {
 void AudioMixerAlsa::SetMuted(bool muted) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   base::AutoLock lock(lock_);
+  if (is_mute_locked_)
+    return;
   is_muted_ = muted;
   if (!apply_is_pending_)

[Daniel Erat, 2012/08/27 17:38:35]

nit: add curly braces since the statement doesn't fit on a single line

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

Done.

     thread_->message_loop()->PostTask(FROM_HERE,
         base::Bind(&AudioMixerAlsa::ApplyState, base::Unretained(this)));
 }
 
+bool AudioMixerAlsa::IsMuteLocked() {
+  base::AutoLock lock(lock_);
+  return is_mute_locked_;
+}
+
+void AudioMixerAlsa::SetMuteLocked(bool locked) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  base::AutoLock lock(lock_);
+  is_mute_locked_ = locked;
+  if (!apply_is_pending_)

[Daniel Erat, 2012/08/27 17:38:35]

ditto

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

Done.

+    thread_->message_loop()->PostTask(FROM_HERE,
+        base::Bind(&AudioMixerAlsa::ApplyState, base::Unretained(this)));
+}
+
+bool AudioMixerAlsa::IsCaptureMuted() {
+  base::AutoLock lock(lock_);
+  return is_capture_muted_;
+}
+
+void AudioMixerAlsa::SetCaptureMuted(bool muted) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  base::AutoLock lock(lock_);
+  if (is_capture_mute_locked_)
+    return;
+  is_capture_muted_ = muted;
+  if (!apply_is_pending_)

[Daniel Erat, 2012/08/27 17:38:35]

ditto

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

Done.

+    thread_->message_loop()->PostTask(FROM_HERE,
+        base::Bind(&AudioMixerAlsa::ApplyState, base::Unretained(this)));
+}
+
+bool AudioMixerAlsa::IsCaptureMuteLocked() {
+  base::AutoLock lock(lock_);
+  return is_capture_mute_locked_;
+}
+
+void AudioMixerAlsa::SetCaptureMuteLocked(bool locked) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  base::AutoLock lock(lock_);
+  is_capture_mute_locked_ = locked;
+  if (!apply_is_pending_)

[Daniel Erat, 2012/08/27 17:38:35]

mind fixing this one too?

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

Done.

+    thread_->message_loop()->PostTask(FROM_HERE,
+        base::Bind(&AudioMixerAlsa::ApplyState, base::Unretained(this)));

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

Lots of code duplication here. Any chance to fix? Maybe at least wrap the
apply-if-not-pending logic in a function?

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

Done.

+}
+
 void AudioMixerAlsa::Connect() {
   DCHECK(MessageLoop::current() == thread_->message_loop());
   DCHECK(!alsa_mixer_);
@@ -266,11 +317,17 @@ bool AudioMixerAlsa::ConnectInternal() {
 
   VLOG(1) << "Volume range is " << min_volume_db << " dB to "
           << max_volume_db << " dB";
+
+  snd_mixer_elem_t* mic_element = FindElementWithName(handle, kMicElementName);
+  snd_mixer_elem_t* front_mic_element =
+      FindElementWithName(handle, kFrontMicElementName);
   {
     base::AutoLock lock(lock_);
     alsa_mixer_ = handle;
     master_element_ = master_element;
     pcm_element_ = pcm_element;
+    mic_element_ = mic_element;
+    front_mic_element_ = front_mic_element;
     min_volume_db_ = min_volume_db;
     max_volume_db_ = max_volume_db;
     volume_db_ = PercentToDb(initial_volume_percent_);
@@ -301,10 +358,12 @@ void AudioMixerAlsa::ApplyState() {
     return;
 
   bool should_mute = false;
+  bool should_mute_capture = false;
   double new_volume_db = 0;
   {
     base::AutoLock lock(lock_);
     should_mute = is_muted_;
+    should_mute_capture = is_capture_muted_;
     new_volume_db = should_mute ? min_volume_db_ : volume_db_;
     apply_is_pending_ = false;
   }
@@ -325,6 +384,10 @@ void AudioMixerAlsa::ApplyState() {
   }
 
   SetElementMuted(master_element_, should_mute);
+  if (mic_element_)
+    SetElementMuted(mic_element_, should_mute_capture);
+  if (front_mic_element_)
+    SetElementMuted(front_mic_element_, should_mute_capture);
 }
 
 snd_mixer_elem_t* AudioMixerAlsa::FindElementWithName(