headless: Ensure all commands have parameters and return types

headless/lib/browser/domain_h.template

Index: headless/lib/browser/domain_h.template
diff --git a/headless/lib/browser/domain_h.template b/headless/lib/browser/domain_h.template
index cc0e8eb4e9b2da58c217bcb5b590a2d9e5feb4ba..2d146a70b52e34dec2ab6204c39660ee19507539 100644
--- a/headless/lib/browser/domain_h.template
+++ b/headless/lib/browser/domain_h.template
@@ -20,15 +20,7 @@
   {% if command.description %}
   // {{ command.description }}
   {% endif %}
-  {% if "parameters" in command and "returns" in command %}
   void {{method_name}}(std::unique_ptr<{{method_name}}Params> params, base::Callback<void(std::unique_ptr<{{method_name}}Result>)> callback = base::Callback<void(std::unique_ptr<{{method_name}}Result>)>());
-  {% elif "parameters" in command %}
-  void {{method_name}}(std::unique_ptr<{{method_name}}Params> params, base::Callback<void()> callback = base::Callback<void()>());
-  {% elif "returns" in command %}
-  void {{method_name}}(base::Callback<void(std::unique_ptr<{{method_name}}Result>)> callback = base::Callback<void(std::unique_ptr<{{method_name}}Result>)>());
-  {% else %}
-  void {{method_name}}(base::Callback<void()> callback = base::Callback<void()>());
-  {% endif %}
   {# Generate convenience methods that take the required parameters directly. #}
   {# Don't generate these for experimental commands. #}
   {% if "parameters" in command and not command.experimental %}
@@ -40,12 +32,17 @@
       {% if not loop.first %}, {% endif %}
 {{resolve_type(parameter).pass_type}} {{parameter.name | camelcase_to_hacker_style -}}
     {% endfor %}
-    {% if "parameters" in command and not command.parameters[0].get("optional", False) %}, {% endif %}{# -#}
-    {% if "returns" in command -%}
+    {% if command.get("parameters", []) and not command.parameters[0].get("optional", False) %}, {% endif %}{# -#}
+    {% if command.get("returns", []) -%}
       base::Callback<void(std::unique_ptr<{{method_name}}Result>)> callback = base::Callback<void(std::unique_ptr<{{method_name}}Result>)>(){##}
     {% else -%}
       base::Callback<void()> callback = base::Callback<void()>(){##}
     {% endif %});
+    {# If the command has no return value, generate a convenience method that #}
+    {# accepts a base::Callback<void()> together with the parameters object. #}
+    {% if not command.get("returns", []) %}
+  void {{method_name}}(std::unique_ptr<{{method_name}}Params> params, base::Callback<void()> callback);
+    {% endif %}
   {% endif %}
 {% endmacro %}