json_schema_compiler: Don't use deprecated ListValue::Append(Value*) overload.

tools/json_schema_compiler/test/additional_properties_unittest.cc

Index: tools/json_schema_compiler/test/additional_properties_unittest.cc
diff --git a/tools/json_schema_compiler/test/additional_properties_unittest.cc b/tools/json_schema_compiler/test/additional_properties_unittest.cc
index 4e2476b0e002f00529f327b532b42e07b648fdf8..f62729c46e29a5192dae720a970725fe234db8b8 100644
--- a/tools/json_schema_compiler/test/additional_properties_unittest.cc
+++ b/tools/json_schema_compiler/test/additional_properties_unittest.cc
@@ -44,7 +44,7 @@ TEST(JsonSchemaCompilerAdditionalPropertiesTest,
   param_object_value->SetString("str", "a");
   param_object_value->SetInteger("num", 1);
   std::unique_ptr<base::ListValue> params_value(new base::ListValue());
-  params_value->Append(param_object_value->DeepCopy());
+  params_value->Append(param_object_value->CreateDeepCopy());
   std::unique_ptr<AdditionalProperties::Params> params(
       AdditionalProperties::Params::Create(*params_value));
   EXPECT_TRUE(params.get());