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

mojo/public/tools/bindings/generators/mojom_js_generator.py

 # Copyright 2013 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.
 
 """Generates JavaScript source files from a mojom.Module."""
 
 import mojom.generate.generator as generator
 import mojom.generate.module as mojom
 import mojom.generate.pack as pack
 from mojom.generate.template_expander import UseJinja
@@ skipping 13 matching lines @@
   mojom.MSGPIPE:               "null",
   mojom.SHAREDBUFFER:          "null",
   mojom.NULLABLE_HANDLE:       "null",
   mojom.NULLABLE_DCPIPE:       "null",
   mojom.NULLABLE_DPPIPE:       "null",
   mojom.NULLABLE_MSGPIPE:      "null",
   mojom.NULLABLE_SHAREDBUFFER: "null",
   mojom.INT64:                 "0",
   mojom.UINT64:                "0",
   mojom.DOUBLE:                "0",
-  mojom.STRING:                '""',
-  mojom.NULLABLE_STRING:       '""'
+  mojom.STRING:                "null",
+  mojom.NULLABLE_STRING:       "null"
 }
 
 
 def JavaScriptType(kind):
   if kind.imported_from:
     return kind.imported_from["unique_name"] + "." + kind.name
   return kind.name
 
 
 def JavaScriptDefaultValue(field):
@@ skipping 220 matching lines @@
     self.Write(self.GenerateJsModule(), "%s.js" % self.module.name)
 
   def GetImports(self):
     # Since each import is assigned a variable in JS, they need to have unique
     # names.
     counter = 1
     for each in self.module.imports:
       each["unique_name"] = "import" + str(counter)
       counter += 1
     return self.module.imports