headless: Replace headless::Maybe with base::Optional

headless/lib/browser/types_cc.template

 // This file is generated
 
 // 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.
 
 #include "headless/public/domains/types.h"
 
 #include "base/memory/ptr_util.h"
 #include "headless/public/domains/type_conversions.h"
@@ skipping 65 matching lines @@
 
   std::unique_ptr<{{type.id}}> result(new {{type.id}}());
   errors->Push();
   errors->SetName("{{type.id}}");
     {% for property in type.properties %}
       {% set value_name = property.name | camelcase_to_hacker_style + "_value" %}
   const base::Value* {{value_name}};
   if (object->Get("{{property.name}}", &{{value_name}})) {
     errors->SetName("{{property.name}}");
       {% if property.optional %}
-    result->{{property.name | camelcase_to_hacker_style}}_ = Just(internal::FromValue<{{resolve_type(property).raw_type}}>::Parse(*{{value_name}}, errors));
+    result->{{property.name | camelcase_to_hacker_style}}_ = internal::FromValue<{{resolve_type(property).raw_type}}>::Parse(*{{value_name}}, errors);
       {% else %}
     result->{{property.name | camelcase_to_hacker_style}}_ = internal::FromValue<{{resolve_type(property).raw_type}}>::Parse(*{{value_name}}, errors);
       {% endif %}
       {% if property.optional %}
   }
       {% else %}
   } else {
     errors->AddError("required property missing: {{property.name}}");
   }
       {% endif %}
     {% endfor %}
   errors->Pop();
   errors->Pop();
   if (errors->HasErrors())
     return nullptr;
   return result;
 }
 
 std::unique_ptr<base::Value> {{type.id}}::Serialize() const {
   std::unique_ptr<base::DictionaryValue> result(new base::DictionaryValue());
     {% for property in type.properties %}
       {% set type = resolve_type(property) %}
       {% if property.optional %}
-  if ({{property.name | camelcase_to_hacker_style}}_.IsJust())
-    result->Set("{{property.name}}", internal::ToValue({{type.to_raw_type % ("%s_.FromJust()" % property.name | camelcase_to_hacker_style)}}));
+  if ({{property.name | camelcase_to_hacker_style}}_)
+    result->Set("{{property.name}}", internal::ToValue({{type.to_raw_type % ("%s_.value()" % property.name | camelcase_to_hacker_style)}}));
       {% else %}
   result->Set("{{property.name}}", internal::ToValue({{type.to_raw_type % ("%s_" % property.name | camelcase_to_hacker_style)}}));
       {% endif %}
     {% endfor %}
   return std::move(result);
 }
 
 std::unique_ptr<{{type.id}}> {{type.id}}::Clone() const {
   ErrorReporter errors;
   std::unique_ptr<{{type.id}}> result = Parse(*Serialize(), &errors);
   DCHECK(!errors.HasErrors());
   return result;
 }
 
   {% endfor %}
 }  // namespace {{domain.domain | camelcase_to_hacker_style}}
 {% endfor %}
 
 } // namespace headless