Remove base::Value::CreateNullValue

services/preferences/tracked/pref_hash_calculator_unittest.cc

Index: services/preferences/tracked/pref_hash_calculator_unittest.cc
diff --git a/services/preferences/tracked/pref_hash_calculator_unittest.cc b/services/preferences/tracked/pref_hash_calculator_unittest.cc
index c4ded422c78a9edf507a75968fb0bb8d48c7746a..df3746a09e0da5014d9b556332b06413a6794903 100644
--- a/services/preferences/tracked/pref_hash_calculator_unittest.cc
+++ b/services/preferences/tracked/pref_hash_calculator_unittest.cc
@@ -76,7 +76,7 @@ TEST(PrefHashCalculatorTest, CatchHashChanges) {
   static const char kSeed[] = "0123456789ABCDEF0123456789ABCDEF";
   static const char kDeviceId[] = "test_device_id1";
 
-  std::unique_ptr<base::Value> null_value = base::Value::CreateNullValue();
+  auto null_value = base::MakeUnique<base::Value>();
   std::unique_ptr<base::Value> bool_value(new base::Value(false));
   std::unique_ptr<base::Value> int_value(new base::Value(1234567890));
   std::unique_ptr<base::Value> double_value(new base::Value(123.0987654321));