bindings: Use forward declarations for wrapper types in dictionary_impl

third_party/WebKit/Source/bindings/scripts/v8_dictionary.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Generate template contexts of dictionaries for both v8 bindings and
 implementation classes that are used by blink's core/modules.
 """
 
 import operator
 from idl_types import IdlType
@@ skipping 143 matching lines @@
         members_dict = {}
         for member in members:
             cpp_name = member['cpp_name']
             duplicated_member = members_dict.get(cpp_name)
             if duplicated_member and duplicated_member != member:
                 raise Exception('Member name conflict: %s' % cpp_name)
             members_dict[cpp_name] = member
         return sorted(members_dict.values(), key=lambda member: member['cpp_name'])
 
     includes.clear()
+    header_forward_decls = set()

[peria, 2016/11/11 03:06:38]

I think we rarely use forward declarations in .cpp file,
so I recommend to remove "header_" from this variable's name.
(optional)

     header_includes = set(['platform/heap/Handle.h'])
-    members = [member_impl_context(member, interfaces_info, header_includes)
+    members = [member_impl_context(member, interfaces_info,
+                                   header_includes, header_forward_decls)
                for member in dictionary.members]
     members = remove_duplicate_members(members)
     context = {
+        'header_forward_decls': header_forward_decls,

[peria, 2016/11/11 03:06:38]

ditto. for the key.

         'header_includes': header_includes,
         'cpp_class': v8_utilities.cpp_name(dictionary),
         'members': members,
     }
     if dictionary.parent:
         context['parent_cpp_class'] = v8_utilities.cpp_name_from_interfaces_info(
             dictionary.parent, interfaces_info)
         parent_interface_info = interfaces_info.get(dictionary.parent)
         if parent_interface_info:
             context['header_includes'].add(
                 parent_interface_info['include_path'])
     else:
         context['parent_cpp_class'] = 'IDLDictionaryBase'
         context['header_includes'].add(
             'bindings/core/v8/IDLDictionaryBase.h')
     return context
 
 
-def member_impl_context(member, interfaces_info, header_includes):
+def member_impl_context(member, interfaces_info, header_includes,
+                        header_forward_decls):
     idl_type = unwrap_nullable_if_needed(member.idl_type)
     cpp_name = v8_utilities.cpp_name(member)
 
     def getter_expression():
         if idl_type.impl_should_use_nullable_container:
             return 'm_%s.get()' % cpp_name
         return 'm_%s' % cpp_name
 
     def has_method_expression():
         if idl_type.impl_should_use_nullable_container or idl_type.is_enum or idl_type.is_string_type or idl_type.is_union_type:
             return '!m_%s.isNull()' % cpp_name
         elif idl_type.name in ['Any', 'Object']:
             return '!(m_{0}.isEmpty() || m_{0}.isNull() || m_{0}.isUndefined())'.format(cpp_name)
         elif idl_type.name == 'Dictionary':
             return '!m_%s.isUndefinedOrNull()' % cpp_name
         else:
             return 'm_%s' % cpp_name
 
     def member_cpp_type():
         member_cpp_type = idl_type.cpp_type_args(used_in_cpp_sequence=True)
         if idl_type.impl_should_use_nullable_container:
             return v8_types.cpp_template_type('Nullable', member_cpp_type)
         return member_cpp_type
 
     cpp_default_value = None
     if member.default_value and not member.default_value.is_null:
         cpp_default_value = idl_type.literal_cpp_value(member.default_value)
 
-    header_includes.update(idl_type.impl_includes_for_type(interfaces_info))
+    forward_decl_name = idl_type.impl_forward_declaration_name
+    if forward_decl_name:
+        includes.update(idl_type.impl_includes_for_type(interfaces_info))
+        header_forward_decls.add(forward_decl_name)
+    else:
+        header_includes.update(idl_type.impl_includes_for_type(interfaces_info))
+
     return {
         'cpp_default_value': cpp_default_value,
         'cpp_name': cpp_name,
         'getter_expression': getter_expression(),
         'has_method_expression': has_method_expression(),
         'has_method_name': has_method_name_for_dictionary_member(member),
         'is_nullable': idl_type.is_nullable,
         'is_traceable': idl_type.is_traceable,
         'member_cpp_type': member_cpp_type(),
         'null_setter_name': null_setter_name_for_dictionary_member(member),
         'rvalue_cpp_type': idl_type.cpp_type_args(used_as_rvalue_type=True),
         'setter_name': setter_name_for_dictionary_member(member),
     }