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

chrome/browser/invalidation/fake_invalidation_service.h

 // Copyright 2013 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.
 
 #ifndef CHROME_BROWSER_INVALIDATION_FAKE_INVALIDATION_SERVICE_H_
 #define CHROME_BROWSER_INVALIDATION_FAKE_INVALIDATION_SERVICE_H_
 
 #include <list>
 #include <utility>
 
@@ skipping 15 matching lines @@
 
 // An InvalidationService that emits invalidations only when
 // its EmitInvalidationForTest method is called.
 class FakeInvalidationService : public InvalidationService {
  public:
   FakeInvalidationService();
   ~FakeInvalidationService() override;
 
   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;
@@ skipping 16 matching lines @@
   syncer::MockAckHandler mock_ack_handler_;
   FakeProfileOAuth2TokenService token_service_;
   FakeIdentityProvider identity_provider_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeInvalidationService);
 };
 
 }  // namespace invalidation
 
 #endif  // CHROME_BROWSER_INVALIDATION_FAKE_INVALIDATION_SERVICE_H_