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

components/invalidation/p2p_invalidation_service.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.
 
 #include "base/callback_forward.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/non_thread_safe.h"
 #include "components/invalidation/invalidation_service.h"
 #include "components/invalidation/p2p_invalidator.h"
 #include "components/keyed_service/core/keyed_service.h"
@@ skipping 22 matching lines @@
   P2PInvalidationService(
       scoped_ptr<IdentityProvider> identity_provider,
       const scoped_refptr<net::URLRequestContextGetter>& request_context,
       syncer::P2PNotificationTarget notification_target);
   ~P2PInvalidationService() override;
 
   // InvalidationService implementation.
   // It is an error to have registered handlers when the service is destroyed.
   void RegisterInvalidationHandler(
       syncer::InvalidationHandler* handler) override;
-  void UpdateRegisteredInvalidationIds(syncer::InvalidationHandler* handler,
+  bool UpdateRegisteredInvalidationIds(syncer::InvalidationHandler* handler,
                                        const syncer::ObjectIdSet& ids) override;
   void UnregisterInvalidationHandler(
       syncer::InvalidationHandler* handler) override;
   syncer::InvalidatorState GetInvalidatorState() const override;
   std::string GetInvalidatorClientId() const override;
   InvalidationLogger* GetInvalidationLogger() override;
   void RequestDetailedStatus(
       base::Callback<void(const base::DictionaryValue&)> caller) const override;
   IdentityProvider* GetIdentityProvider() override;
 
   void UpdateCredentials(const std::string& username,
                          const std::string& password);
 
   void SendInvalidation(const syncer::ObjectIdSet& ids);
 
  private:
   scoped_ptr<IdentityProvider> identity_provider_;
   scoped_ptr<syncer::P2PInvalidator> invalidator_;
   std::string invalidator_id_;
 
   DISALLOW_COPY_AND_ASSIGN(P2PInvalidationService);
 };
 
 }  // namespace invalidation
 
 #endif  // COMPONENTS_INVALIDATION_P2P_INVALIDATION_SERVICE_H_