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

tools/json_schema_compiler/test/test_util.h

Index: tools/json_schema_compiler/test/test_util.h
diff --git a/tools/json_schema_compiler/test/test_util.h b/tools/json_schema_compiler/test/test_util.h
index d82e90512d5c1dc38acc53296283ab3c8f672a4b..87145fda5a4e7afa0c39c8da13235e3c7b7d0362 100644
--- a/tools/json_schema_compiler/test/test_util.h
+++ b/tools/json_schema_compiler/test/test_util.h
@@ -34,6 +34,8 @@ std::vector<T> Vector(const T& a, const T& b, const T& c) {
   return arr;
 }
 
+// TODO(dcheng): These various helpers should all take std::unique_ptr
+// arguments. See https://crbug.com/581865.
 std::unique_ptr<base::ListValue> List(base::Value* a);
 std::unique_ptr<base::ListValue> List(base::Value* a, base::Value* b);
 std::unique_ptr<base::ListValue> List(base::Value* a,