[Bindings] Move and remove some private symbols from V8HiddenValue

third_party/WebKit/Source/modules/fetch/Request.cpp

 // 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.
 
 #include "modules/fetch/Request.h"
 
 #include "bindings/core/v8/Dictionary.h"
+#include "bindings/core/v8/V8PrivateProperty.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/loader/ThreadableLoader.h"
 #include "modules/fetch/BodyStreamBuffer.h"
 #include "modules/fetch/FetchManager.h"
 #include "modules/fetch/RequestInit.h"
 #include "platform/HTTPNames.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/loader/fetch/FetchUtils.h"
 #include "platform/loader/fetch/ResourceLoaderOptions.h"
@@ skipping 703 matching lines @@
   v8::Local<v8::Value> bodyBuffer = ToV8(this->bodyBuffer(), scriptState);
   v8::Local<v8::Value> request = ToV8(this, scriptState);
   if (request.IsEmpty()) {
     // |toV8| can return an empty handle when the worker is terminating.
     // We don't want the renderer to crash in such cases.
     // TODO(yhirano): Delete this block after the graceful shutdown
     // mechanism is introduced.
     return;
   }
   DCHECK(request->IsObject());
-  V8HiddenValue::setHiddenValue(
-      scriptState, request.As<v8::Object>(),
-      V8HiddenValue::internalBodyBuffer(scriptState->isolate()), bodyBuffer);
+  V8PrivateProperty::getInternalBodyBuffer(scriptState->isolate())
+      .set(request.As<v8::Object>(), bodyBuffer);

[haraken, 2017/03/30 14:04:45]

This private property is set but never get.

Is it probably used to keep alive the body buffer? If that is the case, we
should replace it with the wrapper tracing. You don't need to address it in this
CL though.

[peria, 2017/04/04 05:48:58]

Those private properties you commented on seem to be used
to keep other wrappers alive.
I'll do it in another CL.

 }
 
 DEFINE_TRACE(Request) {
   Body::trace(visitor);
   visitor->trace(m_request);
   visitor->trace(m_headers);
 }
 
 }  // namespace blink