Modify the volume visuals:

chrome/browser/chromeos/audio/audio_handler.cc

 // 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.
 
 #include "chrome/browser/chromeos/audio/audio_handler.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/logging.h"
@@ skipping 68 matching lines @@
   local_state->ClearPref(prefs::kAudioVolumeDb);
   local_state->UnregisterPreference(prefs::kAudioVolumeDb);
 }
 
 double AudioHandler::GetVolumePercent() {
   return mixer_->GetVolumePercent();
 }
 
 void AudioHandler::SetVolumePercent(double volume_percent) {
   volume_percent = min(max(volume_percent, 0.0), 100.0);
+  if (IsMuted() && volume_percent > 0.0)
+    SetMuted(false);
   mixer_->SetVolumePercent(volume_percent);
   prefs_->SetDouble(prefs::kAudioVolumePercent, volume_percent);
   FOR_EACH_OBSERVER(VolumeObserver, volume_observers_, OnVolumeChanged());
 }
 
 void AudioHandler::AdjustVolumeByPercent(double adjust_by_percent) {
   SetVolumePercent(mixer_->GetVolumePercent() + adjust_by_percent);
 }
 
 bool AudioHandler::IsMuted() {
@@ skipping 24 matching lines @@
   mixer_->SetVolumePercent(prefs_->GetDouble(prefs::kAudioVolumePercent));
   mixer_->SetMuted(prefs_->GetInteger(prefs::kAudioMute) == kPrefMuteOn);
   mixer_->Init();
 }
 
 AudioHandler::~AudioHandler() {
   mixer_.reset();
 };
 
 }  // namespace chromeos