[Origin Trials] Install origin trial bindings on V8 context conditionally

third_party/WebKit/Source/bindings/templates/partial_interface.h

 {% include 'copyright_block.txt' %}
 #ifndef {{v8_class_or_partial}}_h
 #define {{v8_class_or_partial}}_h
 
 {% for filename in header_includes %}
 #include "{{filename}}"
 {% endfor %}
 
 namespace blink {
 
 class {{v8_class_or_partial}} {
     STATIC_ONLY({{v8_class_or_partial}});
 public:
     static void initialize();
     {% for method in methods if method.is_custom %}
     static void {{method.name}}MethodCustom(const v8::FunctionCallbackInfo<v8::Value>&);
     {% endfor %}
     {% for attribute in attributes %}
     {% if attribute.has_custom_getter %}{# FIXME: and not attribute.implemented_by #}
     static void {{attribute.name}}AttributeGetterCustom(const v8::PropertyCallbackInfo<v8::Value>&);
     {% endif %}
     {% if attribute.has_custom_setter %}{# FIXME: and not attribute.implemented_by #}
     static void {{attribute.name}}AttributeSetterCustom(v8::Local<v8::Value>, const v8::PropertyCallbackInfo<void>&);
     {% endif %}
     {% endfor %}
     {# Custom internal fields #}
     static void preparePrototypeAndInterfaceObject(v8::Local<v8::Context>, const DOMWrapperWorld&, v8::Local<v8::Object>, v8::Local<v8::Function>, v8::Local<v8::FunctionTemplate>);
+    {% for group in attributes|origin_trial_enabled_attributes|groupby('origin_trial_feature_name') %}{{newline}}
+    static void install{{group.grouper}}(v8::Isolate*, const DOMWrapperWorld&, v8::Local<v8::Object> instance, v8::Local<v8::Function> interface);
+    {% endfor %}
 private:
     static void install{{v8_class}}Template(v8::Isolate*, const DOMWrapperWorld&, v8::Local<v8::FunctionTemplate> interfaceTemplate);
 };
 }
 #endif // {{v8_class_or_partial}}_h