Introduce infrastructure for tracing ScriptWrappables.

third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.cpp

Index: third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.cpp b/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..84a5d125b4edd705b3fdd46967290ab3dda2de82
--- /dev/null
+++ b/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.cpp
@@ -0,0 +1,62 @@
+// Copyright 2016 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 "bindings/core/v8/ScriptWrappableVisitor.h"
+
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "bindings/core/v8/ScriptWrappableHeapTracer.h"
+#include "core/dom/NodeRareData.h"
+#include "core/events/EventListenerMap.h"
+#include "core/events/EventTarget.h"
+#include "platform/heap/HeapPage.h"
+
+namespace blink {
+
+bool ScriptWrappableVisitor::isMarked(const void* garbageCollected) const
+{
+    return HeapObjectHeader::fromPayload(garbageCollected)->isDOMMarked();
+}
+
+void ScriptWrappableVisitor::mark(const ScriptWrappable* scriptWrappable) const
+{
+    mark(static_cast<const void*>(scriptWrappable));
+
+    if (scriptWrappable->containsWrapper())

[haraken, 2016/04/13 12:26:22]

It would be better to move this check into ScriptWrappable::markWrapperAlive.

[Marcel Hlopko, 2016/04/14 16:39:08]

Done.

+        scriptWrappable->markWrapperAlive(m_isolate);
+}
+
+void ScriptWrappableVisitor::mark(const void* garbageCollected) const
+{
+    HeapObjectHeader* header = HeapObjectHeader::fromPayload(garbageCollected);
+    header->markDOM();
+    m_tracer->AddHeaderToUnmark(header);
+}
+
+void ScriptWrappableVisitor::markHandle(v8::Persistent<v8::Object>& handle) const
+{
+    ScriptWrappable::markWrapperAlive(handle, m_isolate);
+}
+
+void ScriptWrappableVisitor::trace(const ScriptWrappable* wrappable) const
+{
+    if (wrappable && !isMarked(wrappable)) {
+        mark(wrappable);
+        wrappable->traceWrappers(this);
+    }
+}
+
+void ScriptWrappableVisitor::trace(const ScriptWrappable& wrappable) const
+{
+    trace(&wrappable);
+}
+
+void ScriptWrappableVisitor::trace(const NodeRareData* data) const

[haraken, 2016/04/13 11:09:05]

Do we need to add a trace(const T*) method every time we trace a DOM object that
is not ScriptWrappable?

[Marcel Hlopko, 2016/04/13 11:11:57]

Yes. Do you have a better approach in mind?

+{
+    if (data && !isMarked(data)) {
+        mark(data);
+        data->traceWrappers(this);
+    }
+}
+
+} // namespace blink