[Sync] InvalidationService shouldn't CHECK when registering ObjectId for more than one handler

components/invalidation/non_blocking_invalidator.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // An implementation of SyncNotifier that wraps InvalidationNotifier
 // on its own thread.
 
 #ifndef COMPONENTS_INVALIDATION_NON_BLOCKING_INVALIDATOR_H_
 #define COMPONENTS_INVALIDATION_NON_BLOCKING_INVALIDATOR_H_
 
@@ skipping 37 matching lines @@
       const std::string& invalidation_bootstrap_data,
       InvalidationStateTracker* invalidation_state_tracker,
       const std::string& client_info,
       const scoped_refptr<net::URLRequestContextGetter>&
           request_context_getter);
 
   ~NonBlockingInvalidator() override;
 
   // Invalidator implementation.
   void RegisterHandler(InvalidationHandler* handler) override;
-  void UpdateRegisteredIds(InvalidationHandler* handler,
+  bool UpdateRegisteredIds(InvalidationHandler* handler,
                            const ObjectIdSet& ids) override;
   void UnregisterHandler(InvalidationHandler* handler) override;
   InvalidatorState GetInvalidatorState() const override;
   void UpdateCredentials(const std::string& email,
                          const std::string& token) override;
   void RequestDetailedStatus(base::Callback<void(const base::DictionaryValue&)>
                                  callback) const override;
 
   // Static functions to construct callback that creates network channel for
   // SyncSystemResources. The goal is to pass network channel to invalidator at
@@ skipping 34 matching lines @@
   scoped_refptr<base::SingleThreadTaskRunner> network_task_runner_;
 
   base::WeakPtrFactory<NonBlockingInvalidator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NonBlockingInvalidator);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_INVALIDATION_NON_BLOCKING_INVALIDATOR_H_