Consolidate volume control code.

chrome/browser/chromeos/system/ash_system_tray_delegate.cc

Index: chrome/browser/chromeos/system/ash_system_tray_delegate.cc
diff --git a/chrome/browser/chromeos/system/ash_system_tray_delegate.cc b/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
index b2b78a5013e65e3897b319b146f39685a8f967c3..8c8d4487f15313571499a6802dc2af503580b5a9 100644
--- a/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
+++ b/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
@@ -337,22 +337,6 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
     chrome::ShowHelp(GetAppropriateBrowser(), chrome::HELP_SOURCE_MENU);
   }
 
-  virtual bool IsAudioMuted() const OVERRIDE {
-    return AudioHandler::GetInstance()->IsMuted();
-  }
-
-  virtual void SetAudioMuted(bool muted) OVERRIDE {
-    return AudioHandler::GetInstance()->SetMuted(muted);
-  }
-
-  virtual float GetVolumeLevel() const OVERRIDE {
-    return AudioHandler::GetInstance()->GetVolumePercent() / 100.f;
-  }
-
-  virtual void SetVolumeLevel(float level) OVERRIDE {
-    AudioHandler::GetInstance()->SetVolumePercent(level * 100.f);
-  }
-
   virtual bool IsCapsLockOn() const OVERRIDE {
     input_method::InputMethodManager* ime_manager =
         input_method::InputMethodManager::GetInstance();