Consolidate volume control code.

ash/system/tray/system_tray_item.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 "ash/system/tray/system_tray_item.h"
 
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray.h"
 #include "ash/system/tray/tray_constants.h"
 #include "ash/system/tray/tray_item_view.h"
@@ skipping 40 matching lines @@
   Shell::GetInstance()->system_tray()->ShowDetailedView(this, 0, true,
       BUBBLE_USE_EXISTING);
 }
 
 void SystemTrayItem::UpdateAfterLoginStatusChange(user::LoginStatus status) {
 }
 
 void SystemTrayItem::UpdateAfterShelfAlignmentChange(ShelfAlignment alignment) {
 }
 
+void SystemTrayItem::UpdateAfterAshInit() {
+}
+
 void SystemTrayItem::PopupDetailedView(int for_seconds, bool activate) {
   Shell::GetInstance()->system_tray()->ShowDetailedView(
       this, for_seconds, activate, BUBBLE_CREATE_NEW);
 }
 
 void SystemTrayItem::SetDetailedViewCloseDelay(int for_seconds) {
   Shell::GetInstance()->system_tray()->SetDetailedViewCloseDelay(for_seconds);
 }
 
 void SystemTrayItem::HideDetailedView() {
   Shell::GetInstance()->system_tray()->HideDetailedView(this);
 }
 
 void SystemTrayItem::ShowNotificationView() {
   Shell::GetInstance()->system_tray()->ShowNotificationView(this);
 }
 
 void SystemTrayItem::HideNotificationView() {
   Shell::GetInstance()->system_tray()->HideNotificationView(this);
 }
 
 }  // namespace ash