Add the boilerplate for actions to File System Provider API.

tools/json_schema_compiler/test/idl_basics.idl

Index: tools/json_schema_compiler/test/idl_basics.idl
diff --git a/tools/json_schema_compiler/test/idl_basics.idl b/tools/json_schema_compiler/test/idl_basics.idl
index 463574f258ff4fc9afa1ef477e139ce975dc85c1..9ee49229460cdde6c2c7a64eb4b56cd937aece46 100644
--- a/tools/json_schema_compiler/test/idl_basics.idl
+++ b/tools/json_schema_compiler/test/idl_basics.idl
@@ -31,6 +31,11 @@
     DOMString x;
   };
 
+  dictionary UnionType {
+    (EnumType or DOMString)? x;
+    (DOMString or EnumType) y;
+  };
+
   callback Callback1 = void();
   callback Callback2 = void(long x);
   callback Callback3 = void(MyType1 arg);