Add support for XFWM titlebar buttons.

chrome/browser/ui/gtk/gconf_titlebar_listener.h

Index: chrome/browser/ui/gtk/gconf_titlebar_listener.h
===================================================================
--- chrome/browser/ui/gtk/gconf_titlebar_listener.h	(revision 164859)
+++ chrome/browser/ui/gtk/gconf_titlebar_listener.h	(working copy)
@@ -12,35 +12,23 @@
 #include <string>
 
 #include "base/basictypes.h"
+#include "chrome/browser/ui/gtk/titlebar_listener.h"
 #include "ui/base/gtk/gtk_signal.h"
 
-class BrowserTitlebar;
-template <typename T> struct DefaultSingletonTraits;
-
 // On GNOME desktops, subscribes to the gconf key which controlls button order.
-// Everywhere else, SetTiltebarButtons() just calls back into BrowserTitlebar
+// Everywhere else, SetTitlebarButtons() just calls back into BrowserTitlebar
 // with the default ordering.
-//
-// Meant to be used as a Singleton through base/memory/singleton.h's interface.
-class GConfTitlebarListener {
+class GConfTitlebarListener : public TitlebarListener::Delegate {
  public:
-  // Returns the singleton instance.
-  static GConfTitlebarListener* GetInstance();
+  GConfTitlebarListener();
 
-  // Sets the current titlebar button order. On GNOME desktops, also subscribes
-  // to further notifications when this changes.
-  void SetTitlebarButtons(BrowserTitlebar* titlebar);
-
-  // Removes |titlebar| from the list of objects observing button order change
-  // notifications.
-  void RemoveObserver(BrowserTitlebar* titlebar);
-
- protected:
+ private:
+  // Refcounted.
   ~GConfTitlebarListener();
 
- private:
-  // Private constructor to enforce singleton access.
-  GConfTitlebarListener();
+  // TitlebarListener::Delegate implementation.
+  virtual bool Init() OVERRIDE;
+  virtual std::string GetCurrentValue() OVERRIDE;
 
   // Called whenever the metacity key changes.
   CHROMEG_CALLBACK_2(GConfTitlebarListener, void, OnChangeNotification,
@@ -61,10 +49,6 @@
   // The current button ordering as heard from gconf.
   std::string current_value_;
 
-  // BrowserTitlebar objects which have subscribed to updates.
-  std::set<BrowserTitlebar*> titlebars_;
-
-  friend struct DefaultSingletonTraits<GConfTitlebarListener>;
   DISALLOW_COPY_AND_ASSIGN(GConfTitlebarListener);
 };