[Autofill] Add typemap for autofill:FormFieldData and autofill::FormData.

components/autofill/content/public/interfaces/test_autofill_types.mojom

Index: components/autofill/content/public/interfaces/test_autofill_types.mojom
diff --git a/components/autofill/content/public/interfaces/test_autofill_types.mojom b/components/autofill/content/public/interfaces/test_autofill_types.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..134fcf347ac4cf7d50913430d25eaa2a6f6a2dfa
--- /dev/null
+++ b/components/autofill/content/public/interfaces/test_autofill_types.mojom
@@ -0,0 +1,12 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module autofill.mojom;
+
+import "components/autofill/content/public/interfaces/autofill_types.mojom";
+
+interface TypeTraitsTest {
+  PassFormData(FormData s) => (FormData passed);
+  PassFormFieldData(FormFieldData s) => (FormFieldData passed);
+};