[Bindings] Create and use V8 context snapshots

third_party/WebKit/Source/platform/bindings/V8DOMWrapper.cpp

 /*
  * Copyright (C) 2009 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
@@ skipping 47 matching lines @@
     // cache resulting objects or their constructors.
     const DOMWrapperWorld& world = DOMWrapperWorld::World(scope.GetContext());
     wrapper = type->domTemplate(isolate, world)
                   ->InstanceTemplate()
                   ->NewInstance(scope.GetContext())
                   .ToLocalChecked();
   }
   return wrapper;
 }
 
+namespace {
+
+v8::Local<v8::Function> ConstructPlainType(v8::Isolate* isolate,

[Yuki, 2017/05/30 14:35:57]

Why don't you remove this function?

[peria, 2017/06/01 08:33:34]

Done.

+                                           const DOMWrapperWorld& world,
+                                           v8::Local<v8::Context> context,
+                                           const WrapperTypeInfo* type) {
+  v8::Context::Scope scope(context);
+  // We shouldn't reach this point for the types that are implemented in v8 such
+  // as typed arrays and hence don't have domTemplateFunction.
+  DCHECK(type->dom_template_function);
+  v8::Local<v8::FunctionTemplate> interface_template =
+      type->domTemplate(isolate, world);
+  // Getting the function might fail if we're running out of stack or memory.
+  v8::Local<v8::Function> interface_object;
+  if (!interface_template->GetFunction(context).ToLocal(&interface_object))
+    return v8::Local<v8::Function>();
+
+  if (type->parent_class) {
+    v8::Local<v8::Object> prototype_template =
+        ConstructPlainType(isolate, world, context, type->parent_class);
+    CHECK(interface_object->SetPrototype(context, prototype_template)
+              .ToChecked());
+  }
+
+  v8::Local<v8::Value> prototype_value;
+  CHECK(interface_object->Get(context, V8AtomicString(isolate, "prototype"))
+            .ToLocal(&prototype_value));
+  CHECK(prototype_value->IsObject());
+  v8::Local<v8::Object> prototype_object = prototype_value.As<v8::Object>();
+  if (prototype_object->InternalFieldCount() ==
+          kV8PrototypeInternalFieldcount &&
+      type->wrapper_type_prototype ==
+          WrapperTypeInfo::kWrapperTypeObjectPrototype) {
+    prototype_object->SetAlignedPointerInInternalField(
+        kV8PrototypeTypeIndex, const_cast<WrapperTypeInfo*>(type));
+  }
+  type->PreparePrototypeAndInterfaceObject(
+      context, world, prototype_object, interface_object, interface_template);
+
+  return interface_object;
+}
+
+}  // namespace
+
 bool V8DOMWrapper::IsWrapper(v8::Isolate* isolate, v8::Local<v8::Value> value) {
   if (value.IsEmpty() || !value->IsObject())
     return false;
   v8::Local<v8::Object> object = v8::Local<v8::Object>::Cast(value);
 
   if (object->InternalFieldCount() < kV8DefaultWrapperInternalFieldCount)
     return false;
 
   const WrapperTypeInfo* untrusted_wrapper_type_info =
       ToWrapperTypeInfo(object);
@@ skipping 12 matching lines @@
     return false;
 
   const ScriptWrappable* untrusted_script_wrappable = ToScriptWrappable(object);
   const WrapperTypeInfo* untrusted_wrapper_type_info =
       ToWrapperTypeInfo(object);
   return untrusted_script_wrappable && untrusted_wrapper_type_info &&
          untrusted_wrapper_type_info->gin_embedder == gin::kEmbedderBlink;
 }
 
 }  // namespace blink