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

components/sync/driver/glue/sync_backend_host_impl.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 "components/sync/driver/glue/sync_backend_host_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/feature_list.h"
@@ skipping 36 matching lines @@
     const scoped_refptr<base::SingleThreadTaskRunner>& ui_thread,
     invalidation::InvalidationService* invalidator,
     const base::WeakPtr<SyncPrefs>& sync_prefs,
     const base::FilePath& sync_folder)
     : frontend_task_runner_(base::ThreadTaskRunnerHandle::Get()),
       sync_client_(sync_client),
       ui_thread_(ui_thread),
       name_(name),
       initialized_(false),
       sync_prefs_(sync_prefs),
-      frontend_(NULL),
+      frontend_(nullptr),
       cached_passphrase_type_(PassphraseType::IMPLICIT_PASSPHRASE),
       invalidator_(invalidator),
       invalidation_handler_registered_(false),
       weak_ptr_factory_(this) {
   core_ = new SyncBackendHostCore(name_, sync_folder,
                                   sync_prefs_->IsFirstSetupComplete(),
                                   weak_ptr_factory_.GetWeakPtr());
 }
 
 SyncBackendHostImpl::~SyncBackendHostImpl() {
@@ skipping 150 matching lines @@
   // pending. This scenario is a valid race, and SetDecryptionPassphrase can
   // trigger a new OnPassphraseRequired if it needs to.
   NotifyPassphraseAccepted();
   return true;
 }
 
 void SyncBackendHostImpl::StopSyncingForShutdown() {
   DCHECK(frontend_task_runner_->BelongsToCurrentThread());
 
   // Immediately stop sending messages to the frontend.
-  frontend_ = NULL;
+  frontend_ = nullptr;
 
   DCHECK(registrar_->sync_thread()->IsRunning());
 
   registrar_->RequestWorkerStopOnUIThread();
 
   core_->ShutdownOnUIThread();
 }
 
 std::unique_ptr<base::Thread> SyncBackendHostImpl::Shutdown(
     ShutdownReason reason) {
   // StopSyncingForShutdown() (which nulls out |frontend_|) should be
   // called first.
   DCHECK(!frontend_);
   DCHECK(registrar_->sync_thread()->IsRunning());
 
   bool sync_thread_claimed = (reason != BROWSER_SHUTDOWN);
 
   if (invalidation_handler_registered_) {
     if (reason == DISABLE_SYNC) {
       UnregisterInvalidationIds();
     }
     invalidator_->UnregisterInvalidationHandler(this);
-    invalidator_ = NULL;
+    invalidator_ = nullptr;
   }
   invalidation_handler_registered_ = false;
 
   model_type_connector_.reset();
 
   // Shut down and destroy sync manager.
   registrar_->sync_thread()->task_runner()->PostTask(
       FROM_HERE,
       base::Bind(&SyncBackendHostCore::DoShutdown, core_, reason));
-  core_ = NULL;
+  core_ = nullptr;
 
   // Worker cleanup.
   SyncBackendRegistrar* detached_registrar = registrar_.release();
   detached_registrar->sync_thread()->task_runner()->PostTask(
       FROM_HERE, base::Bind(&SyncBackendRegistrar::Shutdown,
                             base::Unretained(detached_registrar)));
 
   if (sync_thread_claimed)
     return detached_registrar->ReleaseSyncThread();
   else
@@ skipping 545 matching lines @@
     const SyncManager::ClearServerDataCallback& frontend_callback) {
   DCHECK(ui_thread_->BelongsToCurrentThread());
   frontend_callback.Run();
 }
 
 }  // namespace syncer
 
 #undef SDVLOG
 
 #undef SLOG