Introduce CustomElementRegistry#get() method

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..abd21d8186ccdca30714240e78b364c5f03cee99 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp
@@ -23,6 +23,15 @@
 
 namespace blink {
 
+namespace {
+
+const int kConstructorIndex = 0;
+const int kPrototypeIndex = 1;
+const int kSizeOfIdMapEntry = 2;
+
+} // namespace
+
+
 CustomElementsRegistry* CustomElementsRegistry::create(
     ScriptState* scriptState,
     V0CustomElementRegistrationContext* v0)
@@ -137,10 +146,13 @@ void CustomElementsRegistry::define(ScriptState* scriptState,
     // This map is stored in a hidden reference from the
     // CustomElementsRegistry wrapper.
     v8::Local<v8::Map> map = idMap(scriptState);
+    v8::Local<v8::Array> mapEntry = v8::Array::New(isolate, kSizeOfIdMapEntry);
+    v8CallOrCrash(mapEntry->Set(context, kConstructorIndex, constructor));
+    v8CallOrCrash(mapEntry->Set(context, kPrototypeIndex, prototype));
     // The map keeps the constructor and prototypes alive.
     v8CallOrCrash(map->Set(context, constructor, idValue));
-    v8CallOrCrash(map->Set(context, idValue, prototype));
-    m_names.add(name);
+    v8CallOrCrash(map->Set(context, idValue, mapEntry));
+    m_names.add(name, id);
 
     // TODO(dominicc): Implement steps:
     // 20: when-defined promise processing
@@ -157,15 +169,33 @@ CustomElementDefinition* CustomElementsRegistry::definitionForConstructor(
     return m_definitions[id];
 }
 
+// https://html.spec.whatwg.org/multipage/scripting.html#dom-customelementsregistry-get
+ScriptValue CustomElementsRegistry::get(
+    ScriptState* scriptState,
+    const AtomicString& name)
+{
+    DCHECK(scriptState->world().isMainWorld());
+    const auto& it = m_names.find(name);
+    if (it == m_names.end())
+        return ScriptValue(scriptState, v8Undefined());
+    v8::Local<v8::Context> context = scriptState->context();
+    v8::Local<v8::Map> map = idMap(scriptState);
+    v8::Local<v8::Value> mapEntry = v8CallOrCrash(
+        map->Get(context, toV8(it->value, scriptState)));
+    DCHECK(mapEntry->IsArray()) << *v8::String::Utf8Value(mapEntry);
+    v8::Local<v8::Value> result = v8CallOrCrash(
+        mapEntry.As<v8::Array>()->Get(context, kConstructorIndex));
+    return ScriptValue(scriptState, result);
+}
+
 v8::Local<v8::Object> CustomElementsRegistry::prototype(
     ScriptState* scriptState,
     const CustomElementDefinition& def)
 {
-    v8::Local<v8::Value> idValue =
-        v8::Integer::NewFromUnsigned(scriptState->isolate(), def.id());
-    return v8CallOrCrash(
-        idMap(scriptState)->Get(scriptState->context(), idValue))
-        .As<v8::Object>();
+    v8::Local<v8::Value> idValue = toV8(def.id(), scriptState);
+    v8::Local<v8::Value> mapEntry = v8CallOrCrash(
+        idMap(scriptState)->Get(scriptState->context(), idValue));
+    return mapEntry.As<v8::Array>()->Get(kPrototypeIndex).As<v8::Object>();
 }
 
 bool CustomElementsRegistry::nameIsDefined(const AtomicString& name) const
@@ -173,6 +203,8 @@ bool CustomElementsRegistry::nameIsDefined(const AtomicString& name) const
     return m_names.contains(name);
 }
 
+// Note: Since |toV8(this, scriptState)| requires non-const pointer, we can't
+// make |idMap()| as const function.
 v8::Local<v8::Map> CustomElementsRegistry::idMap(ScriptState* scriptState)
 {
     DCHECK(scriptState->world().isMainWorld());