Have bindings layer assume and insist that all interface types are GCed.

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 168 matching lines @@
     base_idl_type = idl_type.base_type
     extended_attributes = attribute.extended_attributes
 
     cpp_value = getter_expression(interface, attribute, context)
     # Normally we can inline the function call into the return statement to
     # avoid the overhead of using a Ref<> temporary, but for some cases
     # (nullable types, EventHandler, [CachedAttribute], or if there are
     # exceptions), we need to use a local variable.
     # FIXME: check if compilers are smart enough to inline this, and if so,
     # always use a local variable (for readability and CG simplicity).
-    release = False
     if 'ImplementedInPrivateScript' in extended_attributes:
         if (not idl_type.is_wrapper_type and
             not idl_type.is_basic_type and
             not idl_type.is_enum):
             raise Exception('Private scripts supports only primitive types and DOM wrappers.')
 
         context['cpp_value_original'] = cpp_value
         cpp_value = 'result'
-        # EventHandler has special handling
-        if base_idl_type != 'EventHandler':
-            release = idl_type.release
     elif (idl_type.is_explicit_nullable or
         base_idl_type == 'EventHandler' or
         'CachedAttribute' in extended_attributes or
         'ReflectOnly' in extended_attributes or
         context['is_keep_alive_for_gc'] or
         context['is_getter_raises_exception']):
         context['cpp_value_original'] = cpp_value
         cpp_value = 'cppValue'
-        # EventHandler has special handling
-        if base_idl_type != 'EventHandler':
-            release = idl_type.release
 
     def v8_set_return_value_statement(for_main_world=False):
         if context['is_keep_alive_for_gc'] or 'CachedAttribute' in extended_attributes:
             return 'v8SetReturnValue(info, v8Value)'
         return idl_type.v8_set_return_value(
             cpp_value, extended_attributes=extended_attributes, script_wrappable='impl',
-            release=release, for_main_world=for_main_world, is_static=attribute.is_static)
+            for_main_world=for_main_world, is_static=attribute.is_static)
 
     context.update({
         'cpp_value': cpp_value,
         'cpp_value_to_v8_value': idl_type.cpp_value_to_v8_value(
             cpp_value=cpp_value, creation_context='holder',
             extended_attributes=extended_attributes),
         'v8_set_return_value_for_main_world': v8_set_return_value_statement(for_main_world=True),
         'v8_set_return_value': v8_set_return_value_statement(),
     })
 
@@ skipping 14 matching lines @@
     if ('PartialInterfaceImplementedAs' in attribute.extended_attributes and
         not 'ImplementedInPrivateScript' in attribute.extended_attributes and
         not attribute.is_static):
         arguments.append('*impl')
     if attribute.idl_type.is_explicit_nullable:
         arguments.append('isNull')
     if context['is_getter_raises_exception']:
         arguments.append('exceptionState')
     if attribute.idl_type.use_output_parameter_for_result:
         arguments.append('result')
-    return '%s(%s)' % (getter_name, ', '.join(arguments))
+
+    expression = '%s(%s)' % (getter_name, ', '.join(arguments))
+    # Needed to handle getter expressions returning Type& as the
+    # use site for |expression| expects Type*.
+    if attribute.idl_type.is_interface_type and len(arguments) == 0:
+        return 'WTF::getPtr(%s)' % expression
+    return expression
 
 
 CONTENT_ATTRIBUTE_GETTER_NAMES = {
     'boolean': 'fastHasAttribute',
     'long': 'getIntegralAttribute',
     'unsigned long': 'getUnsignedIntegralAttribute',
 }
 
 
 def getter_base_name(interface, attribute, arguments):
@@ skipping 122 matching lines @@
     elif idl_type.base_type == 'EventHandler':
         getter_name = scoped_name(interface, attribute, cpp_name(attribute))
         context['event_handler_getter_expression'] = '%s(%s)' % (
             getter_name, ', '.join(arguments))
         if (interface.name in ['Window', 'WorkerGlobalScope'] and
             attribute.name == 'onerror'):
             includes.add('bindings/core/v8/V8ErrorHandler.h')
             arguments.append('V8EventListenerList::findOrCreateWrapper<V8ErrorHandler>(v8Value, true, ScriptState::current(info.GetIsolate()))')
         else:
             arguments.append('V8EventListenerList::getEventListener(ScriptState::current(info.GetIsolate()), v8Value, true, ListenerFindOrCreate)')
-    elif idl_type.is_interface_type:
-        # FIXME: should be able to eliminate WTF::getPtr in most or all cases
-        arguments.append('WTF::getPtr(cppValue)')
     else:
         arguments.append('cppValue')
     if context['is_setter_raises_exception']:
         arguments.append('exceptionState')
 
     return '%s(%s)' % (setter_name, ', '.join(arguments))
 
 
 CONTENT_ATTRIBUTE_SETTER_NAMES = {
     'boolean': 'setBooleanAttribute',
@@ skipping 108 matching lines @@
     lambda self: strip_suffix(self.base_type, 'Constructor'))
 
 
 def is_constructor_attribute(attribute):
     # FIXME: replace this with [ConstructorAttribute] extended attribute
     return attribute.idl_type.name.endswith('Constructor')
 
 
 def update_constructor_attribute_context(interface, attribute, context):
     context['needs_constructor_getter_callback'] = context['measure_as'] or context['deprecate_as'] or context['origin_trial_enabled_function']  # TODO(chasej): Should/can this be true when OriginTrialEnabled is inherited from containing interface?