First implementation of lazily cached accessor for DOM attributes.

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

Index: third_party/WebKit/Source/bindings/scripts/v8_attributes.py
diff --git a/third_party/WebKit/Source/bindings/scripts/v8_attributes.py b/third_party/WebKit/Source/bindings/scripts/v8_attributes.py
index cf11eb50400c06a6d625dd7afb40e2f903922ebd..a6d02f5103e89ff6455a5768b5ac421b291f64a4 100644
--- a/third_party/WebKit/Source/bindings/scripts/v8_attributes.py
+++ b/third_party/WebKit/Source/bindings/scripts/v8_attributes.py
@@ -117,6 +117,7 @@ def attribute_context(interface, attribute, interfaces):
     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]
@@ -140,6 +141,7 @@ def attribute_context(interface, attribute, interfaces):
         '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,