[bindings] Implement an ExperimentEnabled IDL extended attribute.

third_party/WebKit/Source/bindings/templates/constants.cpp

+{% from 'utilities.cpp' import check_api_experiment %}
+
 {##############################################################################}
 {% macro constant_getter_callback(constant) %}
 {% filter conditional(constant.conditional_string) %}
 static void {{constant.name}}ConstantGetterCallback(v8::Local<v8::Name>, const v8::PropertyCallbackInfo<v8::Value>& info)
 {
     TRACE_EVENT_SET_SAMPLING_STATE("blink", "DOMGetter");
     {% if constant.deprecate_as %}
     UseCounter::countDeprecationIfNotPrivateScript(info.GetIsolate(), callingExecutionContext(info.GetIsolate()), UseCounter::{{constant.deprecate_as}});
     {% endif %}
     {% if constant.measure_as %}
     UseCounter::countIfNotPrivateScript(info.GetIsolate(), callingExecutionContext(info.GetIsolate()), UseCounter::{{constant.measure_as('ConstantGetter')}});
     {% endif %}
+    {% if constant.is_api_experiment_enabled %}
+    {{check_api_experiment(constant) | indent}}
+    {% endif %}
     {% if constant.idl_type in ('Double', 'Float') %}
     v8SetReturnValue(info, {{constant.value}});
     {% elif constant.idl_type == 'String' %}
     v8SetReturnValueString(info, "{{constant.value}}");
     {% else %}
     v8SetReturnValueInt(info, {{constant.value}});
     {% endif %}
     TRACE_EVENT_SET_SAMPLING_STATE("v8", "V8Execution");
 }
 {% endfilter %}
@@ skipping 14 matching lines @@
 {# Runtime-enabled constants #}
 {% for constant_tuple in runtime_enabled_constants %}
 {% filter runtime_enabled(constant_tuple[0]) %}
 {% for constant in constant_tuple[1] %}
 {% set constant_name = constant.name.title().replace('_', '') %}
 const V8DOMConfiguration::ConstantConfiguration constant{{constant_name}}Configuration = {{constant_configuration(constant)}};
 V8DOMConfiguration::installConstant(isolate, functionTemplate, prototypeTemplate, constant{{constant_name}}Configuration);
 {% endfor %}
 {% endfilter %}
 {% endfor %}
-{# Constants with [DeprecateAs] or [MeasureAs] #}
+{# Constants with [DeprecateAs] or [MeasureAs] or [APIExperimentEnabled] #}
 {% for constant in special_getter_constants %}
 V8DOMConfiguration::installConstantWithGetter(isolate, functionTemplate, prototypeTemplate, "{{constant.name}}", {{cpp_class}}V8Internal::{{constant.name}}ConstantGetterCallback);
 {% endfor %}
 {# Check constants #}
 {% if not do_not_check_constants %}
 {% for constant in constants %}
 {% if constant.idl_type not in ('Double', 'Float', 'String') %}
 {% set constant_cpp_class = constant.cpp_class or cpp_class %}
 static_assert({{constant.value}} == {{constant_cpp_class}}::{{constant.reflected_name}}, "the value of {{cpp_class}}_{{constant.reflected_name}} does not match with implementation");
 {% endif %}
 {% endfor %}
 {% endif %}
 {% endmacro %}
 
 
 {######################################}
 {%- macro constant_configuration(constant) %}
 {% if constant.idl_type in ('Double', 'Float') %}
     {% set value = '0, %s' % constant.value %}
 {% else %}
     {# 'Short', 'Long' etc. #}
     {% set value = '%s, 0' % constant.value %}
 {% endif %}
 {"{{constant.name}}", {{value}}, V8DOMConfiguration::ConstantType{{constant.idl_type}}}
 {%- endmacro %}