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

chrome/browser/chromeos/system_key_event_listener.h

Index: chrome/browser/chromeos/system_key_event_listener.h
===================================================================
--- chrome/browser/chromeos/system_key_event_listener.h	(revision 118753)
+++ chrome/browser/chromeos/system_key_event_listener.h	(working copy)
@@ -28,7 +28,17 @@
   class CapsLockObserver {
    public:
     virtual void OnCapsLockChange(bool enabled) = 0;
+   protected:
+    virtual ~CapsLockObserver() {}
   };
+
+  class StatusAreaVolumeObserver {
+   public:
+    virtual void ShowStatusAreaVolume(bool show) = 0;
+   protected:
+    virtual ~StatusAreaVolumeObserver() {}
+  };
+
   static void Initialize();
   static void Shutdown();
   // GetInstance returns NULL if not initialized or if already shutdown.
@@ -39,6 +49,9 @@
   void AddCapsLockObserver(CapsLockObserver* observer);
   void RemoveCapsLockObserver(CapsLockObserver* observer);
 
+  void AddStatusAreaVolumeObserver(StatusAreaVolumeObserver* observer);
+  void RemoveStatusAreaVolumeObserver(StatusAreaVolumeObserver* observer);
+
  private:
   // Defines the delete on exit Singleton traits we like.  Best to have this
   // and const/dest private as recommended for Singletons.
@@ -78,6 +91,7 @@
   void OnVolumeDown();
   void OnVolumeUp();
   void OnCapsLock(bool enabled);
+  void ShowStatusAreaVolume(bool show);
 
   // Displays the volume bubble for the current volume and muting status.
   // Also hides the brightness bubble if it's being shown.
@@ -99,10 +113,14 @@
 
   bool stopped_;
 
+  bool show_status_area_volume_;

[xiyuan, 2012/01/25 04:43:12]

Add a comment that this controls whether or not to show volume button in status
area and is mutually exclusive with VolumeBubble.

[achuithb, 2012/01/25 10:46:06]

Done.

+
   const unsigned int num_lock_mask_;
   bool num_lock_is_on_;
   bool caps_lock_is_on_;
+
   ObserverList<CapsLockObserver> caps_lock_observers_;
+  ObserverList<StatusAreaVolumeObserver> status_area_volume_observers_;
 
   // Base X ID for events from the XKB extension.
   int xkb_event_base_;