The default value for NullableString should be null (was "")

mojo/public/js/bindings/codec_unittests.js

 // Copyright 2014 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.
 
 define([
     "gin/test/expect",
     "mojo/public/js/bindings/codec",
     "mojo/public/interfaces/bindings/tests/rect.mojom",
     "mojo/public/interfaces/bindings/tests/sample_service.mojom",
     "mojo/public/interfaces/bindings/tests/test_structs.mojom",
@@ skipping 170 matching lines @@
       builder.encodeStruct(cls, input)
       var message = builder.finish();
 
       var reader = new codec.MessageReader(message);
       expect(reader.payloadSize).toBe(payloadSize);
       expect(reader.messageName).toBe(messageName);
       var result = reader.decodeStruct(cls);
       expect(result).toEqual(expectedResult);
     }
     encodeDecode(codec.String, "banana", "banana", 24);
+    encodeDecode(codec.NullableString, null, null, 8);
     encodeDecode(codec.Int8, -1, -1);
     encodeDecode(codec.Int8, 0xff, -1);
     encodeDecode(codec.Int16, -1, -1);
     encodeDecode(codec.Int16, 0xff, 0xff);
     encodeDecode(codec.Int16, 0xffff, -1);
     encodeDecode(codec.Int32, -1, -1);
     encodeDecode(codec.Int32, 0xffff, 0xffff);
     encodeDecode(codec.Int32, 0xffffffff, -1);
     encodeDecode(codec.Float, 1.0, 1.0);
     encodeDecode(codec.Double, 1.0, 1.0);
@@ skipping 47 matching lines @@
     expect(actualMemory.length).toEqual(expectedMemory.length);
     expect(actualMemory).toEqual(expectedMemory);
 
     var reader = new codec.MessageReader(message);
     expect(reader.payloadSize).toBe(payloadSize);
     expect(reader.messageName).toBe(messageName);
     var str2 = reader.decoder.decodeStringPointer();
     expect(str2).toEqual(str);
   }
 });