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

components/sync/test/fake_server/fake_server.h

 // Copyright 2014 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 COMPONENTS_SYNC_TEST_FAKE_SERVER_FAKE_SERVER_H_
 #define COMPONENTS_SYNC_TEST_FAKE_SERVER_FAKE_SERVER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 212 matching lines @@
   EntityMap entities_;
 
   // All Keystore keys known to the server.
   std::vector<std::string> keystore_keys_;
 
   // Used as the error_code field of ClientToServerResponse on all responses
   // except when |triggered_actionable_error_| is set.
   sync_pb::SyncEnums::ErrorType error_type_;
 
   // Used as the error field of ClientToServerResponse when its pointer is not
-  // NULL.
+  // null.
   std::unique_ptr<sync_pb::ClientToServerResponse_Error>
       triggered_actionable_error_;
 
   // These values are used in tandem to return a triggered error (either
   // |error_type_| or |triggered_actionable_error_|) on every other request.
   // |alternate_triggered_errors_| is set if this feature is enabled and
   // |request_counter_| is used to send triggered errors on odd-numbered
   // requests. Note that |request_counter_| can be reset and is not necessarily
   // indicative of the total number of requests handled during the object's
   // lifetime.
@@ skipping 15 matching lines @@
   base::ThreadChecker thread_checker_;
 
   // Creates WeakPtr versions of the current FakeServer. This must be the last
   // data member!
   base::WeakPtrFactory<FakeServer> weak_ptr_factory_;
 };
 
 }  // namespace fake_server
 
 #endif  // COMPONENTS_SYNC_TEST_FAKE_SERVER_FAKE_SERVER_H_