Draft change to use base::Closure instead of PrefObserver in PrefChangeRegistrar.

chrome/browser/prefs/pref_service.h

Index: chrome/browser/prefs/pref_service.h
diff --git a/chrome/browser/prefs/pref_service.h b/chrome/browser/prefs/pref_service.h
index ff4585ccd2d63d4bcf0285476d7f1edb5c6837b1..ba5253f86fed0b696be14b9f4803b27180dddf25 100644
--- a/chrome/browser/prefs/pref_service.h
+++ b/chrome/browser/prefs/pref_service.h
@@ -28,7 +28,6 @@ class PersistentPrefStore;
 class PrefModelAssociator;
 class PrefNotifier;
 class PrefNotifierImpl;
-class PrefObserver;
 class PrefServiceObserver;
 class PrefStore;
 class PrefValueStore;
@@ -307,9 +306,9 @@ class PrefService : public PrefServiceBase, public base::NonThreadSafe {
 
   // PrefServiceBase implementation (protected in base, private here).
   virtual void AddPrefObserver(const char* path,
-                               PrefObserver* obs) OVERRIDE;
+                               const base::Closure& obs) OVERRIDE;
   virtual void RemovePrefObserver(const char* path,
-                                  PrefObserver* obs) OVERRIDE;
+                                  const base::Closure& obs) OVERRIDE;
 
   // Sends notification of a changed preference. This needs to be called by
   // a ScopedUserPrefUpdate if a DictionaryValue or ListValue is changed.