Support for showing/hiding status area volume controls in desktop devices

chrome/browser/chromeos/status/volume_menu_button.h

Index: chrome/browser/chromeos/status/volume_menu_button.h
===================================================================
--- chrome/browser/chromeos/status/volume_menu_button.h	(revision 118753)
+++ chrome/browser/chromeos/status/volume_menu_button.h	(working copy)
@@ -8,15 +8,18 @@
 
 #include "base/compiler_specific.h"
 #include "chrome/browser/chromeos/status/status_area_button.h"
+#include "chrome/browser/chromeos/system_key_event_listener.h"
 #include "ui/views/controls/menu/menu_delegate.h"
 #include "ui/views/controls/menu/view_menu_delegate.h"
 
 namespace chromeos {
 
 // The volume button in the status area.
-class VolumeMenuButton : public StatusAreaButton,
-                         public views::MenuDelegate,
-                         public views::ViewMenuDelegate {
+class VolumeMenuButton
+    : public StatusAreaButton,
+      public views::MenuDelegate,
+      public views::ViewMenuDelegate,
+      public SystemKeyEventListener::StatusAreaVolumeObserver {
  public:
   explicit VolumeMenuButton(StatusAreaButton::Delegate* delegate);
   virtual ~VolumeMenuButton();
@@ -35,6 +38,9 @@
   // views::ViewMenuDelegate implementation.
   virtual void RunMenu(views::View* source, const gfx::Point& pt) OVERRIDE;
 
+  // SystemKeyEventListener::StatusAreaVolumeObserver implementation.
+  virtual void ShowStatusAreaVolume(bool show) OVERRIDE;
+
   DISALLOW_COPY_AND_ASSIGN(VolumeMenuButton);
 };