[SyncFS] Use nullptr instead of NULL

chrome/browser/sync_file_system/drive_backend/conflict_resolver_unittest.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/conflict_resolver.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
@@ skipping 53 matching lines @@
         drive_uploader(new FakeDriveUploader(fake_drive_service.get()));
     fake_drive_helper_.reset(
         new FakeDriveServiceHelper(fake_drive_service.get(),
                                    drive_uploader.get(),
                                    kSyncRootFolderTitle));
     remote_change_processor_.reset(new FakeRemoteChangeProcessor);
 
     context_.reset(new SyncEngineContext(
         fake_drive_service.PassAs<drive::DriveServiceInterface>(),
         drive_uploader.Pass(),
-        NULL,
+        nullptr,
         base::ThreadTaskRunnerHandle::Get(),
         base::ThreadTaskRunnerHandle::Get()));
     context_->SetRemoteChangeProcessor(remote_change_processor_.get());
 
     RegisterSyncableFileSystem();
 
     sync_task_manager_.reset(new SyncTaskManager(
         base::WeakPtr<SyncTaskManager::Client>(),
         10 /* maximum_background_task */,
         base::ThreadTaskRunnerHandle::Get()));
@@ skipping 433 matching lines @@
 
   EXPECT_EQ(4, CountParents(file));
 
   EXPECT_EQ(SYNC_STATUS_OK, RunConflictResolver());
 
   EXPECT_EQ(1, CountParents(file));
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system