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

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

 // Copyright 2016 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/sync_arc_package_helper.h"
 
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
@@ skipping 39 matching lines @@
 }  // namespace
 
 SyncArcPackageHelper* SyncArcPackageHelper::GetInstance() {
   SyncArcPackageHelper* instance = base::Singleton<SyncArcPackageHelper>::get();
   DCHECK(sync_datatype_helper::test());
   instance->SetupTest(sync_datatype_helper::test());
   return instance;
 }
 
 SyncArcPackageHelper::SyncArcPackageHelper()
-    : test_(NULL), setup_completed_(false), user_manager_enabler_(nullptr) {}
+    : test_(nullptr), setup_completed_(false), user_manager_enabler_(nullptr) {}
 
 SyncArcPackageHelper::~SyncArcPackageHelper() {}
 
 void SyncArcPackageHelper::SetupTest(SyncTest* test) {
   if (setup_completed_) {
     DCHECK_EQ(test, test_);
     return;
   }
   test_ = test;
 
@@ skipping 180 matching lines @@
     if (package1_info->last_backup_android_id !=
         package2_info->last_backup_android_id)
       return false;
     if (package1_info->last_backup_time != package2_info->last_backup_time)
       return false;
   }
   return true;
 }
 
 }  // namespace arc