First implementation of lazily cached accessor for DOM attributes.

third_party/WebKit/Source/bindings/scripts/v8_attributes.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 99 matching lines @@
 
     cached_attribute_validation_method = extended_attributes.get('CachedAttribute')
     keep_alive_for_gc = is_keep_alive_for_gc(interface, attribute)
     if cached_attribute_validation_method or keep_alive_for_gc:
         includes.add('platform/bindings/V8PrivateProperty.h')
 
     # [CachedAccessor]
     is_cached_accessor = 'CachedAccessor' in extended_attributes
     if is_cached_accessor:
         includes.add('platform/bindings/V8PrivateProperty.h')
+    is_lazy_cached_accessor = is_cached_accessor and extended_attributes.get('CachedAccessor') == 'Lazy'
 
     context = {
         'activity_logging_world_list_for_getter': v8_utilities.activity_logging_world_list(attribute, 'Getter'),  # [ActivityLogging]
         'activity_logging_world_list_for_setter': v8_utilities.activity_logging_world_list(attribute, 'Setter'),  # [ActivityLogging]
         'activity_logging_world_check': v8_utilities.activity_logging_world_check(attribute),  # [ActivityLogging]
         'cached_attribute_validation_method': cached_attribute_validation_method,
         'constructor_type': constructor_type,
         'cpp_name': cpp_name(attribute),
         'cpp_type': idl_type.cpp_type,
         'cpp_type_initializer': idl_type.cpp_type_initializer,
         'deprecate_as': v8_utilities.deprecate_as(attribute),  # [DeprecateAs]
         'enum_type': idl_type.enum_type,
         'enum_values': idl_type.enum_values,
         'exposed_test': v8_utilities.exposed(attribute, interface),  # [Exposed]
         'has_cross_origin_getter':
             has_extended_attribute_value(attribute, 'CrossOrigin', None) or
             has_extended_attribute_value(attribute, 'CrossOrigin', 'Getter'),
         'has_cross_origin_setter': has_extended_attribute_value(attribute, 'CrossOrigin', 'Setter'),
         'has_custom_getter': has_custom_getter(attribute),
         'has_custom_setter': has_custom_setter(attribute),
         'has_setter': has_setter(interface, attribute),
         'idl_type': str(idl_type),  # need trailing [] on array for Dictionary::ConversionContext::setConversionType
         'is_cached_accessor': is_cached_accessor,
+        'is_lazy_cached_accessor': is_lazy_cached_accessor,
         'is_call_with_execution_context': has_extended_attribute_value(attribute, 'CallWith', 'ExecutionContext'),
         'is_call_with_script_state': has_extended_attribute_value(attribute, 'CallWith', 'ScriptState'),
         'is_ce_reactions': is_ce_reactions,
         'is_check_security_for_receiver': is_check_security_for_receiver,
         'is_check_security_for_return_value': is_check_security_for_return_value,
         'is_custom_element_callbacks': is_custom_element_callbacks,
         # TODO(yukishiino): Make all DOM attributes accessor-type properties.
         'is_data_type_property': is_data_type_property(interface, attribute),
         'is_getter_raises_exception':  # [RaisesException]
             'RaisesException' in extended_attributes and
@@ skipping 417 matching lines @@
 def is_constructor_attribute(attribute):
     return attribute.idl_type.name.endswith('Constructor')
 
 
 def is_named_constructor_attribute(attribute):
     return attribute.idl_type.name.endswith('ConstructorConstructor')
 
 
 def update_constructor_attribute_context(interface, attribute, context):
     context['needs_constructor_getter_callback'] = context['measure_as'] or context['deprecate_as']