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

chrome/browser/sync/sync_ui_util.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_BROWSER_SYNC_SYNC_UI_UTIL_H_
 #define CHROME_BROWSER_SYNC_SYNC_UI_UTIL_H_
 
 #include "base/strings/string16.h"
 #include "build/build_config.h"
 
@@ skipping 50 matching lines @@
 MessageType GetStatusLabelsForNewTabPage(
     Profile* profile,
     browser_sync::ProfileSyncService* service,
     const SigninManagerBase& signin,
     base::string16* status_label,
     base::string16* link_label);
 
 #if !defined(OS_CHROMEOS)
 // Gets various labels for the sync global error based on the sync error state.
 // |menu_item_label|, |bubble_message|, and |bubble_accept_label| must not be
-// NULL. Note that we don't use SyncGlobalError on Chrome OS.
+// null. Note that we don't use SyncGlobalError on Chrome OS.
 void GetStatusLabelsForSyncGlobalError(
     const browser_sync::ProfileSyncService* service,
     base::string16* menu_item_label,
     base::string16* bubble_message,
     base::string16* bubble_accept_label);
 
 // Gets the error message and button label for the sync errors that should be
 // exposed to the user through the titlebar avatar button.
 AvatarSyncErrorType GetMessagesForAvatarSyncError(Profile* profile,
                                                   int* content_string_id,
                                                   int* button_string_id);
 #endif
 
 MessageType GetStatus(Profile* profile,
                       browser_sync::ProfileSyncService* service,
                       const SigninManagerBase& signin);
 
 }  // namespace sync_ui_util
 #endif  // CHROME_BROWSER_SYNC_SYNC_UI_UTIL_H_