[Sync] Replacing NULL with nullptr/null throughout sync code.

chrome/browser/sync/test/integration/fake_server_invalidation_service.cc

 // 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 "chrome/browser/sync/test/integration/fake_server_invalidation_service.h"
 
 #include "components/invalidation/impl/invalidation_service_util.h"
 #include "components/invalidation/public/invalidation.h"
 #include "components/invalidation/public/object_id_invalidation_map.h"
 #include "components/sync/base/invalidation_helper.h"
@@ skipping 30 matching lines @@
     const {
   return invalidator_registrar_.GetInvalidatorState();
 }
 
 std::string FakeServerInvalidationService::GetInvalidatorClientId() const {
   return client_id_;
 }
 
 invalidation::InvalidationLogger*
 FakeServerInvalidationService::GetInvalidationLogger() {
-  return NULL;
+  return nullptr;
 }
 
 void FakeServerInvalidationService::RequestDetailedStatus(
     base::Callback<void(const base::DictionaryValue&)> caller) const {
   base::DictionaryValue value;
   caller.Run(value);
 }
 
 IdentityProvider* FakeServerInvalidationService::GetIdentityProvider() {
   return &identity_provider_;
@@ skipping 19 matching lines @@
     // invalidating all items of a given type.
 
     if (self_notify_ || client_id_ != committer_id) {
       invalidation_map.Insert(syncer::Invalidation::InitUnknownVersion(*it));
     }
   }
   invalidator_registrar_.DispatchInvalidationsToHandlers(invalidation_map);
 }
 
 }  // namespace fake_server