[Sync] Replacing NULL with nullptr in code and null in comments for components/sync/

components/sync/device_info/device_info_sync_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 "components/sync/device_info/device_info_sync_service.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <utility>
@@ skipping 28 matching lines @@
 
   DCHECK(!IsSyncing());
 
   sync_processor_ = std::move(sync_processor);
   error_handler_ = std::move(error_handler);
 
   // Initialization should be completed before this type is enabled
   // and local device info must be available.
   const DeviceInfo* local_device_info =
       local_device_info_provider_->GetLocalDeviceInfo();
-  DCHECK(local_device_info != NULL);
+  DCHECK(local_device_info != nullptr);
 
   // Indicates whether a local device has been added or updated.
   // |change_type| defaults to ADD and might be changed to
   // UPDATE to INVALID down below if the initial data contains
   // data matching the local device ID.
   SyncChange::SyncChangeType change_type = SyncChange::ACTION_ADD;
   TimeDelta pulse_delay;
   size_t num_items_new = 0;
   size_t num_items_updated = 0;
 
@@ skipping 255 matching lines @@
     return SyncDataRemote(device_info).GetModifiedTime();
   } else {
     // We shouldn't reach this point for remote data, so this means we're likely
     // looking at the local device info. Using a long ago time is perfect, since
     // the desired behavior is to update/pulse our data as soon as possible.
     return Time();
   }
 }
 
 }  // namespace syncer