[SyncFS] Use nullptr instead of NULL

chrome/browser/sync_file_system/drive_backend/sync_engine.cc

 // 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.
 
 #include "chrome/browser/sync_file_system/drive_backend/sync_engine.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/metrics/histogram.h"
@@ skipping 209 matching lines @@
                      worker_task_runner.get(),
                      drive_task_runner.get(),
                      GetSyncFileSystemDir(context->GetPath()),
                      task_logger,
                      notification_manager,
                      extension_service,
                      signin_manager,
                      token_service,
                      request_context.get(),
                      make_scoped_ptr(new DriveServiceFactory()),
-                     NULL /* env_override */));
+                     nullptr /* env_override */));
 
   sync_engine->Initialize();
   return sync_engine.Pass();
 }
 
 void SyncEngine::AppendDependsOnFactories(
     std::set<BrowserContextKeyedServiceFactory*>* factories) {
   DCHECK(factories);
   factories->insert(drive::DriveNotificationManagerFactory::GetInstance());
   factories->insert(SigninManagerFactory::GetInstance());
@@ skipping 510 matching lines @@
       worker_task_runner_(worker_task_runner),
       drive_task_runner_(drive_task_runner),
       sync_file_system_dir_(sync_file_system_dir),
       task_logger_(task_logger),
       notification_manager_(notification_manager),
       extension_service_(extension_service),
       signin_manager_(signin_manager),
       token_service_(token_service),
       request_context_(request_context),
       drive_service_factory_(drive_service_factory.Pass()),
-      remote_change_processor_(NULL),
+      remote_change_processor_(nullptr),
       service_state_(REMOTE_SERVICE_TEMPORARY_UNAVAILABLE),
       has_refresh_token_(false),
       network_available_(false),
       sync_enabled_(false),
       env_override_(env_override),
       weak_ptr_factory_(this) {
   DCHECK(sync_file_system_dir_.IsAbsolute());
   if (notification_manager_)
     notification_manager_->AddObserver(this);
   if (signin_manager_)
@@ skipping 29 matching lines @@
 
 SyncStatusCallback SyncEngine::TrackCallback(
     const SyncStatusCallback& callback) {
   return callback_tracker_.Register(
       base::Bind(callback, SYNC_STATUS_ABORT),
       callback);
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system