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

chrome/browser/prefs/pref_notifier_impl.h

Index: chrome/browser/prefs/pref_notifier_impl.h
diff --git a/chrome/browser/prefs/pref_notifier_impl.h b/chrome/browser/prefs/pref_notifier_impl.h
index 34c225f96048f16cd59d610a4e0807bd580aef39..e7d2154489c45fe0ea0e8a68a53c77c040326b99 100644
--- a/chrome/browser/prefs/pref_notifier_impl.h
+++ b/chrome/browser/prefs/pref_notifier_impl.h
@@ -12,7 +12,6 @@
 #include "base/hash_tables.h"
 #include "base/observer_list.h"
 #include "base/prefs/pref_notifier.h"
-#include "base/prefs/public/pref_observer.h"
 #include "base/threading/non_thread_safe.h"
 
 class PrefService;
@@ -27,8 +26,13 @@ class PrefNotifierImpl : public PrefNotifier,
 
   // If the pref at the given path changes, we call the observer's
   // OnPreferenceChanged method.
-  void AddPrefObserver(const char* path, PrefObserver* observer);
-  void RemovePrefObserver(const char* path, PrefObserver* observer);
+  void AddPrefObserver(const char* path, const base::Closure& observer);
+
+  // This removes an observer.  Note that when using the Closure
+  // version of the method, you must provide a closure whose Equal()
+  // method will evaluate to true when compared to the closure you
+  // registered using AddPrefObserver.
+  void RemovePrefObserver(const char* path, const base::Closure& observer);
 
   // We run the callback once, when initialization completes. The bool
   // parameter will be set to true for successful initialization,
@@ -45,7 +49,7 @@ class PrefNotifierImpl : public PrefNotifier,
   // A map from pref names to a list of observers. Observers get fired in the
   // order they are added. These should only be accessed externally for unit
   // testing.
-  typedef ObserverList<PrefObserver> PrefObserverList;
+  typedef std::list<base::Closure> PrefObserverList;
   typedef base::hash_map<std::string, PrefObserverList*> PrefObserverMap;
 
   typedef std::list<base::Callback<void(bool)> > PrefInitObserverList;