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

components/sync/driver/shared_change_processor.cc

Index: components/sync/driver/shared_change_processor.cc
diff --git a/components/sync/driver/shared_change_processor.cc b/components/sync/driver/shared_change_processor.cc
index 4b0d57f89ce41a7c183bfc217b4da1fbae0d9251..514609ee3263d42470a77ba8714ec9260338cab2 100644
--- a/components/sync/driver/shared_change_processor.cc
+++ b/components/sync/driver/shared_change_processor.cc
@@ -25,14 +25,14 @@ SharedChangeProcessor::SharedChangeProcessor(ModelType type)
     : disconnected_(false),
       type_(type),
       frontend_task_runner_(base::ThreadTaskRunnerHandle::Get()),
-      generic_change_processor_(NULL) {
+      generic_change_processor_(nullptr) {
   DCHECK_NE(type_, UNSPECIFIED);
 }
 
 SharedChangeProcessor::~SharedChangeProcessor() {
   // We can either be deleted when the DTC is destroyed (on UI
   // thread), or when the SyncableService stops syncing (datatype
-  // thread).  |generic_change_processor_|, if non-NULL, must be
+  // thread).  |generic_change_processor_|, if non-null, must be
   // deleted on |backend_loop_|.
   if (backend_task_runner_.get()) {
     if (backend_task_runner_->BelongsToCurrentThread()) {