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..bb28a752164d268d3ff4776f00d376f265d279b1
--- /dev/null
+++ b/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.cpp
@@ -0,0 +1,104 @@
+// 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/ActiveScriptWrappable.h"
+#include "bindings/core/v8/DOMDataStore.h"
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "bindings/core/v8/WrapperTypeInfo.h"
+#include "core/dom/NodeRareData.h"
+#include "core/events/EventListenerMap.h"
+#include "core/events/EventTarget.h"
+#include "platform/heap/HeapPage.h"
+
+namespace blink {
+
+ScriptWrappableVisitor::~ScriptWrappableVisitor()
+{
+}
+
+void ScriptWrappableVisitor::TracePrologue()
+{
+    m_tracingInProgress = true;
+    ActiveScriptWrappable::traceActiveScriptWrappables(this);
+}
+
+void ScriptWrappableVisitor::TraceEpilogue()
+{
+    for (auto header : m_headersToUnmark)
+        header->unmarkWrapperHeader();
+
+    m_headersToUnmark.clear();
+    m_tracingInProgress = false;
+}
+
+void ScriptWrappableVisitor::TraceWrappersFrom(const std::vector<std::pair<void*, void*>>& internalFieldsOfPotentialWrappers)
+{
+    ASSERT(m_tracingInProgress);
+    for (auto pair : internalFieldsOfPotentialWrappers) {
+        traceWrappersFrom(pair);
+    }
+}
+
+void ScriptWrappableVisitor::traceWrappersFrom(std::pair<void*, void*> internalFields)
+{
+    if (reinterpret_cast<WrapperTypeInfo*>(internalFields.first)->ginEmbedder != gin::GinEmbedder::kEmbedderBlink)
+        return;
+
+    ScriptWrappable* scriptWrappable = reinterpret_cast<ScriptWrappable*>(internalFields.second);
+    ASSERT(scriptWrappable->wrapperTypeInfo()->wrapperClassId == WrapperTypeInfo::NodeClassId
+        || scriptWrappable->wrapperTypeInfo()->wrapperClassId == WrapperTypeInfo::ObjectClassId);
+
+    traceWrappers(scriptWrappable);
+}
+
+bool ScriptWrappableVisitor::isHeaderMarked(const void* garbageCollected) const
+{
+    return HeapObjectHeader::fromPayload(garbageCollected)->isWrapperHeaderMarked();
+}
+
+void ScriptWrappableVisitor::markHeader(const void* garbageCollected) const
+{
+    HeapObjectHeader* header = HeapObjectHeader::fromPayload(garbageCollected);
+    header->markWrapperHeader();
+    addHeaderToUnmark(header);
+}
+
+void ScriptWrappableVisitor::markHeader(const ScriptWrappable* scriptWrappable) const
+{
+    markHeader(static_cast<const void*>(scriptWrappable));
+
+    markWrappersInAllWorlds(scriptWrappable, m_isolate);
+}
+
+void ScriptWrappableVisitor::addHeaderToUnmark(HeapObjectHeader* header) const
+{
+    m_headersToUnmark.append(header);
+}
+
+void ScriptWrappableVisitor::markWrapper(const v8::Persistent<v8::Object>& handle, v8::Isolate* isolate)
+{
+    handle.RegisterExternalReference(isolate);
+}
+
+void ScriptWrappableVisitor::markWrappersInAllWorlds(const ScriptWrappable* scriptWrappable, v8::Isolate* isolate)
+{
+    DOMWrapperWorld::markWrappersInAllWorlds(const_cast<ScriptWrappable*>(scriptWrappable), isolate);
+}
+
+void ScriptWrappableVisitor::traceWrappers(const ScriptWrappable* wrappable) const
+{
+    if (wrappable && !isHeaderMarked(wrappable)) {
+        markHeader(wrappable);
+        wrappable->traceWrappers(this);
+    }
+}
+
+void ScriptWrappableVisitor::traceWrappers(const ScriptWrappable& wrappable) const
+{
+    traceWrappers(&wrappable);
+}
+
+} // namespace blink