binding: Reimplements V8HiddenValue as V8PrivateProperty.

third_party/WebKit/Source/bindings/core/v8/custom/V8MessageEventCustom.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 17 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "bindings/core/v8/V8MessageEvent.h"
 
 #include "bindings/core/v8/SerializedScriptValue.h"
 #include "bindings/core/v8/SerializedScriptValueFactory.h"
 #include "bindings/core/v8/V8ArrayBuffer.h"
 #include "bindings/core/v8/V8Binding.h"
 #include "bindings/core/v8/V8Blob.h"
-#include "bindings/core/v8/V8HiddenValue.h"
 #include "bindings/core/v8/V8MessagePort.h"
+#include "bindings/core/v8/V8PrivateProperty.h"
 #include "bindings/core/v8/V8Window.h"
-#include "core/events/MessageEvent.h"
 
 namespace blink {
 
 void V8MessageEvent::dataAttributeGetterCustom(const v8::FunctionCallbackInfo<v8::Value>& info)
 {
     ScriptState* scriptState = ScriptState::current(info.GetIsolate());
-    v8::Local<v8::Value> cachedData = V8HiddenValue::getHiddenValue(scriptState, info.Holder(), V8HiddenValue::data(info.GetIsolate()));
+    auto privateCachedData = V8PrivateProperty::getMessageEventCachedData(info.GetIsolate());
+    v8::Local<v8::Value> cachedData = privateCachedData.get(scriptState->context(), info.Holder());
     if (!cachedData.IsEmpty()) {
         v8SetReturnValue(info, cachedData);
         return;
     }
 
     MessageEvent* event = V8MessageEvent::toImpl(info.Holder());
 
     v8::Local<v8::Value> result;
     switch (event->getDataType()) {
     case MessageEvent::DataTypeScriptValue:
         result = event->dataAsScriptValue().v8ValueFor(scriptState);
         if (result.IsEmpty())
             result = v8::Null(info.GetIsolate());
         break;
 
     case MessageEvent::DataTypeSerializedScriptValue:
         if (SerializedScriptValue* serializedValue = event->dataAsSerializedScriptValue()) {
             MessagePortArray ports = event->ports();
             result = serializedValue->deserialize(info.GetIsolate(), &ports);
         } else {
             result = v8::Null(info.GetIsolate());
         }
         break;
 
-    case MessageEvent::DataTypeString: {
-        result = V8HiddenValue::getHiddenValue(scriptState, info.Holder(), V8HiddenValue::stringData(info.GetIsolate()));

[haraken, 2016/05/26 16:41:53]

Why can you remove this code?

[Yuki, 2016/05/27 11:49:02]

MessageEvent used three different hidden values before this CL; stringData,
arrayBufferData, and data.  See MessageEvent.cpp, too.  The logic was:

    In MessageEvent.cpp:
    MessageEvent* e;
    save e->dataAsString() into V8HiddenValue::stringData

    In V8MessageEventCustom.cpp:
    if (V8HiddenValue::data exists)
      return V8HiddenValue::data

    result = V8HiddenValue::stringData
    save result into V8HiddenValue::data
    return result

Why don't we directly save the value of e->dataAsString() into
V8HiddenValue::data?

I did it in this CL.  V8HiddenValue::data is renamed to
V8PrivateProperty::getMessageEventCachedData.

-        if (result.IsEmpty()) {
-            String stringValue = event->dataAsString();
-            result = v8String(info.GetIsolate(), stringValue);
-        }
+    case MessageEvent::DataTypeString:
+        result = v8String(info.GetIsolate(), event->dataAsString());
         break;
-    }
 
     case MessageEvent::DataTypeBlob:
         result = toV8(event->dataAsBlob(), info.Holder(), info.GetIsolate());
         break;
 
     case MessageEvent::DataTypeArrayBuffer:
-        result = V8HiddenValue::getHiddenValue(scriptState, info.Holder(), V8HiddenValue::arrayBufferData(info.GetIsolate()));

[haraken, 2016/05/26 16:41:52]

Ditto.

-        if (result.IsEmpty())
-            result = toV8(event->dataAsArrayBuffer(), info.Holder(), info.GetIsolate());
+        result = toV8(event->dataAsArrayBuffer(), info.Holder(), info.GetIsolate());
         break;
     }
 
-    // Store the result as a hidden value so this callback returns the cached
+    // Store the result as a private value so this callback returns the cached
     // result in future invocations.
-    V8HiddenValue::setHiddenValue(scriptState,  info.Holder(), V8HiddenValue::data(info.GetIsolate()), result);
+    privateCachedData.set(scriptState->context(), info.Holder(), result);
     v8SetReturnValue(info, result);
 }
 
 void V8MessageEvent::initMessageEventMethodCustom(const v8::FunctionCallbackInfo<v8::Value>& info)
 {
     ExceptionState exceptionState(ExceptionState::ExecutionContext, "initMessageEvent", "MessageEvent", info.Holder(), info.GetIsolate());
     MessageEvent* event = V8MessageEvent::toImpl(info.Holder());
     TOSTRING_VOID(V8StringResource<>, typeArg, info[0]);
     bool canBubbleArg = false;
     bool cancelableArg = false;
     if (!v8Call(info[1]->BooleanValue(info.GetIsolate()->GetCurrentContext()), canBubbleArg)
         || !v8Call(info[2]->BooleanValue(info.GetIsolate()->GetCurrentContext()), cancelableArg))
         return;
     v8::Local<v8::Value> dataArg = info[3];
     TOSTRING_VOID(V8StringResource<>, originArg, info[4]);
     TOSTRING_VOID(V8StringResource<>, lastEventIdArg, info[5]);
     DOMWindow* sourceArg = toDOMWindow(info.GetIsolate(), info[6]);
     MessagePortArray* portArray = nullptr;
     const int portArrayIndex = 7;
     if (!isUndefinedOrNull(info[portArrayIndex])) {
         portArray = new MessagePortArray;
         *portArray = toMemberNativeArray<MessagePort>(info[portArrayIndex], portArrayIndex + 1, info.GetIsolate(), exceptionState);
         if (exceptionState.throwIfNeeded())
             return;
     }
     event->initMessageEvent(typeArg, canBubbleArg, cancelableArg, ScriptValue(ScriptState::current(info.GetIsolate()), dataArg), originArg, lastEventIdArg, sourceArg, portArray);
 }
 
 } // namespace blink