DevTools: consistently use Maybe for optional values in the protocol generator.

third_party/WebKit/Source/platform/inspector_protocol/Frontend_h.template

 // This file is generated
 
 // Copyright (c) 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.
 
 #ifndef {{class_name}}_h
 #define {{class_name}}_h
 
 
@@ skipping 14 matching lines @@
 
     class PLATFORM_EXPORT {{domain.domain}} {
     public:
         static {{domain.domain}}* from(Frontend* frontend) { return &(frontend->m_{{domain.domain | lower}}) ;}
         {{domain.domain}}(FrontendChannel* frontendChannel) : m_frontendChannel(frontendChannel) { }
   {% for event in domain.events %}
     {% if "handlers" in event and not ("renderer" in event["handlers"]) %}{% continue %}{% endif %}
         void {{event.name}}(
     {%- for parameter in event.parameters -%}
       {%- if "optional" in parameter -%}
-            {{resolve_type(parameter).optional_pass_type}}
-        {%- if resolve_type(parameter).nullable -%}
-              {{parameter.name}} = nullptr
-        {%- else -%}
-              {{parameter.name}} = {{resolve_type(parameter).optional_type}}()
-        {%- endif %}
+            const Maybe<{{resolve_type(parameter).raw_type}}>& {{parameter.name}} = Maybe<{{resolve_type(parameter).raw_type}}>()
       {%- else -%}
             {{resolve_type(parameter).pass_type}} {{parameter.name}}
       {%- endif -%}{%- if not loop.last -%}, {% endif -%}
     {%- endfor -%}
         );
   {% endfor %}
 
         void flush() { m_frontendChannel->flush(); }
     private:
         FrontendChannel* m_frontendChannel;
     };
 {% endfor %}
 
 private:
     FrontendChannel* m_frontendChannel;
 {% for domain in api.domains %}
     {{domain.domain}} m_{{domain.domain | lower}};
 {% endfor %}
 };
 
 } // namespace protocol
 } // namespace blink
 
 #endif // !defined({{class_name}}_h)