[Sync] Avoid unregistering object IDs on shutdown

sync/notifier/p2p_notifier.h

Index: sync/notifier/p2p_notifier.h
diff --git a/sync/notifier/p2p_notifier.h b/sync/notifier/p2p_notifier.h
index d2de89d01cdbdde1ae988710ea4b905ffca0a8bd..4457c6f64905afc60b406e09badce908b4a93d46 100644
--- a/sync/notifier/p2p_notifier.h
+++ b/sync/notifier/p2p_notifier.h
@@ -20,7 +20,7 @@
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/notifier/notifications_disabled_reason.h"
 #include "sync/notifier/sync_notifier.h"
-#include "sync/notifier/sync_notifier_helper.h"
+#include "sync/notifier/sync_notifier_registrar.h"
 
 namespace notifier {
 class PushClient;
@@ -96,8 +96,10 @@ class P2PNotifier : public SyncNotifier,
   virtual ~P2PNotifier();
 
   // SyncNotifier implementation
+  virtual void RegisterHandler(SyncNotifierObserver* handler) OVERRIDE;
   virtual void UpdateRegisteredIds(SyncNotifierObserver* handler,
                                    const ObjectIdSet& ids) OVERRIDE;
+  virtual void UnregisterHandler(SyncNotifierObserver* handler) OVERRIDE;
   virtual void SetUniqueId(const std::string& unique_id) OVERRIDE;
   virtual void SetStateDeprecated(const std::string& state) OVERRIDE;
   virtual void UpdateCredentials(
@@ -119,7 +121,7 @@ class P2PNotifier : public SyncNotifier,
 
   base::ThreadChecker thread_checker_;
 
-  SyncNotifierHelper helper_;
+  SyncNotifierRegistrar registrar_;
 
   // The push client.
   scoped_ptr<notifier::PushClient> push_client_;