Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/ui/gtk/global_menu_bar.h

Index: chrome/browser/ui/gtk/global_menu_bar.h
diff --git a/chrome/browser/ui/gtk/global_menu_bar.h b/chrome/browser/ui/gtk/global_menu_bar.h
index ba72f89ed980706a6f7804c2d3a468acb4273633..a1682d67097074c639747be737f85c5f2d165c62 100644
--- a/chrome/browser/ui/gtk/global_menu_bar.h
+++ b/chrome/browser/ui/gtk/global_menu_bar.h
@@ -9,9 +9,9 @@
 
 #include "base/compiler_specific.h"
 #include "base/prefs/public/pref_change_registrar.h"
+#include "base/prefs/public/pref_observer.h"
 #include "chrome/browser/command_observer.h"
 #include "chrome/browser/ui/gtk/global_history_menu.h"
-#include "content/public/browser/notification_observer.h"
 #include "ui/base/gtk/gtk_signal.h"
 #include "ui/base/gtk/owned_widget_gtk.h"
 
@@ -31,7 +31,7 @@ typedef struct _GtkWidget GtkWidget;
 // bar itself is visible, so we insert a GtkMenuBar into the window hierarchy
 // and set it to be invisible.
 class GlobalMenuBar : public CommandObserver,
-                      public content::NotificationObserver {
+                      public PrefObserver {
  public:
   static const int TAG_NORMAL = 0;
   static const int TAG_MOST_VISITED = 1;
@@ -68,10 +68,9 @@ class GlobalMenuBar : public CommandObserver,
   // CommandObserver:
   virtual void EnabledStateChangedForCommand(int id, bool enabled) OVERRIDE;
 
-  // content::NotificationObserver:
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
+  // PrefObserver:
+  virtual void OnPreferenceChanged(PrefServiceBase* service,
+                                   const std::string& pref_name) OVERRIDE;
 
   // Updates the visibility of the bookmark bar on pref changes.
   void OnBookmarkBarVisibilityChanged();