Make CustomElementsRegistry lazily initialize script state.

third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp

Index: third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp
diff --git a/third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp b/third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp
index 3478c6b4cf5f6f23811b1f505bae7a320310c749..834a2897ebadfb3d6d8d7265165d1381f8d02b15 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp
@@ -24,24 +24,11 @@
 namespace blink {
 
 CustomElementsRegistry* CustomElementsRegistry::create(
-    ScriptState* scriptState,
     V0CustomElementRegistrationContext* v0)
 {
-    DCHECK(scriptState->world().isMainWorld());
     CustomElementsRegistry* registry = new CustomElementsRegistry(v0);
     if (v0)
         v0->setV1(registry);
-
-    v8::Isolate* isolate = scriptState->isolate();
-    v8::Local<v8::Object> wrapper =
-        toV8(registry, scriptState).As<v8::Object>();
-    v8::Local<v8::String> name =
-        V8HiddenValue::customElementsRegistryMap(isolate);
-    v8::Local<v8::Map> map = v8::Map::New(isolate);
-    bool didSetPrototype =
-        V8HiddenValue::setHiddenValue(scriptState, wrapper, name, map);
-    DCHECK(didSetPrototype);
-
     return registry;
 }
 
@@ -173,15 +160,34 @@ bool CustomElementsRegistry::nameIsDefined(const AtomicString& name) const
     return m_names.contains(name);
 }
 
+void CustomElementsRegistry::initializeScript(

[haraken, 2016/05/23 01:46:37]

I'd rename the method to ensureConstructorMap() and make it return the map. Then
the caller site can just call it to get the map.

+    ScriptState* scriptState,
+    v8::Local<v8::Map>& map)
+{
+    CHECK(scriptState->world().isMainWorld());
+    v8::Local<v8::Object> wrapper = toV8(this, scriptState).As<v8::Object>();
+    v8::Isolate* isolate = scriptState->isolate();
+    v8::Local<v8::String> name =
+        V8HiddenValue::customElementsRegistryMap(isolate);
+    DCHECK(V8HiddenValue::getHiddenValue(scriptState, wrapper, name).IsEmpty());
+    map = v8::Map::New(isolate);
+    V8HiddenValue::setHiddenValue(scriptState, wrapper, name, map);
+}
+
 v8::Local<v8::Map> CustomElementsRegistry::idMap(ScriptState* scriptState)
 {
-    DCHECK(scriptState->world().isMainWorld());
-    v8::Local<v8::Object> wrapper =
-        toV8(this, scriptState).As<v8::Object>();
+    CHECK(scriptState->world().isMainWorld());
+    v8::Local<v8::Object> wrapper = toV8(this, scriptState).As<v8::Object>();
     v8::Local<v8::String> name = V8HiddenValue::customElementsRegistryMap(
         scriptState->isolate());
-    return V8HiddenValue::getHiddenValue(scriptState, wrapper, name)
-        .As<v8::Map>();
+    v8::Local<v8::Value> mapValue =
+        V8HiddenValue::getHiddenValue(scriptState, wrapper, name);
+    v8::Local<v8::Map> map;
+    if (!mapValue.IsEmpty())
+        map = mapValue.As<v8::Map>();
+    else
+        initializeScript(scriptState, map);
+    return map;
 }
 
 bool CustomElementsRegistry::idForConstructor(