[C++11 Allowed Features] Declares a type-safe null pointer converting from NULL to nullptr [part-…

cc/trees/layer_sorter.cc

Index: cc/trees/layer_sorter.cc
diff --git a/cc/trees/layer_sorter.cc b/cc/trees/layer_sorter.cc
index e171fe01120f6389931b1acb403581968e7126db..a1e99a1fd4e3783b6f493efb621ee2785bebf7f5 100644
--- a/cc/trees/layer_sorter.cc
+++ b/cc/trees/layer_sorter.cc
@@ -318,8 +318,8 @@ void LayerSorter::CreateGraphEdges() {
                                                     &node_b.shape,
                                                     z_threshold,
                                                     &weight);
-      GraphNode* start_node = NULL;
-      GraphNode* end_node = NULL;
+      GraphNode* start_node = nullptr;
+      GraphNode* end_node = nullptr;
       if (overlap_result == ABeforeB) {
         start_node = &node_a;
         end_node = &node_b;
@@ -429,7 +429,7 @@ void LayerSorter::Sort(LayerImplList::iterator first,
     // will favor nodes that have zero-weight incoming edges i.e. layers that
     // are being occluded by a layer that intersects them.
     float min_incoming_edge_weight = FLT_MAX;
-    GraphNode* next_node = NULL;
+    GraphNode* next_node = nullptr;
     for (size_t i = 0; i < nodes_.size(); i++) {
       if (nodes_[i].incoming.size() &&
           nodes_[i].incoming_edge_weight < min_incoming_edge_weight) {