Convert NULL to nullptr

util/posix/symbolic_constants_posix_test.cc

Index: util/posix/symbolic_constants_posix_test.cc
diff --git a/util/posix/symbolic_constants_posix_test.cc b/util/posix/symbolic_constants_posix_test.cc
index c80d00d9e522b9e1870c132794a44185f1d37174..db3193d45e1840bea680b305baf2610fd3eeceec 100644
--- a/util/posix/symbolic_constants_posix_test.cc
+++ b/util/posix/symbolic_constants_posix_test.cc
@@ -69,7 +69,7 @@ const struct {
 #endif
 };
 
-// If |expect| is NULL, the conversion is expected to fail. If |expect| is
+// If |expect| is nullptr, the conversion is expected to fail. If |expect| is
 // empty, the conversion is expected to succeed, but the precise returned string
 // value is unknown. Otherwise, the conversion is expected to succeed, and
 // |expect| contains the precise expected string value to be returned.
@@ -130,7 +130,7 @@ TEST(SymbolicConstantsPOSIX, SignalToString) {
     if (signal > 0 && signal < kSignalCount) {
       TestSignalToString(signal, "", "");
     } else {
-      TestSignalToString(signal, NULL, NULL);
+      TestSignalToString(signal, nullptr, nullptr);
     }
   }
 }