Implement new slider control and disable the volume control when audio is muted.

chrome/browser/chromeos/system/ash_system_tray_delegate.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/system/ash_system_tray_delegate.h"
 
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/system/audio/audio_observer.h"
 #include "ash/system/bluetooth/bluetooth_observer.h"
@@ skipping 926 matching lines @@
     }
     accessibility::Speak(connection_string.c_str());
   }
 
   // Overridden from AudioHandler::VolumeObserver.
   virtual void OnVolumeChanged() OVERRIDE {
     float level = AudioHandler::GetInstance()->GetVolumePercent() / 100.f;
     tray_->audio_observer()->OnVolumeChanged(level);
   }
 
+  // Overridden from AudioHandler::VolumeObserver.
+  virtual void OnMuteToggled() OVERRIDE {
+    tray_->audio_observer()->OnMuteToggled();
+  }
+
   // Overridden from PowerManagerClient::Observer.
   virtual void BrightnessChanged(int level, bool user_initiated) OVERRIDE {
     tray_->brightness_observer()->
         OnBrightnessChanged(static_cast<double>(level), user_initiated);
   }
 
   virtual void PowerChanged(const PowerSupplyStatus& power_status) OVERRIDE {
     power_supply_status_ = power_status;
     FOR_EACH_OBSERVER(ash::PowerStatusObserver, tray_->power_status_observers(),
         OnPowerStatusChanged(power_status));
@@ skipping 296 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(SystemTrayDelegate);
 };
 
 }  // namespace
 
 ash::SystemTrayDelegate* CreateSystemTrayDelegate(ash::SystemTray* tray) {
   return new chromeos::SystemTrayDelegate(tray);
 }
 
 }  // namespace chromeos