Introduce infrastructure for tracing ScriptWrappables.

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

Index: third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.h b/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.h
new file mode 100644
index 0000000000000000000000000000000000000000..6de1dd6e7b13710cff333674d905ae0974827a83
--- /dev/null
+++ b/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.h
@@ -0,0 +1,75 @@
+// 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.
+
+#ifndef ScriptWrappableVisitor_h
+#define ScriptWrappableVisitor_h
+
+#include "platform/heap/HeapAllocator.h"
+#include <v8.h>
+#include <vector>
+
+
+namespace blink {
+
+class HeapObjectHeader;
+class ScriptWrappable;
+class ScriptWrappableHeapTracer;
+class NodeRareData;
+
+#define DECLARE_VIRTUAL_TRACE_WRAPPABLE()                                  \
+    virtual void traceWrappable(const ScriptWrappableVisitor*) const
+
+#define DECLARE_VIRTUAL_TRACE_WRAPPABLE_CHILDREN()                         \
+    virtual void traceWrappableChildren(const ScriptWrappableVisitor*) const
+
+#define DECLARE_NONVIRTUAL_TRACE_WRAPPABLE()                               \
+    void traceWrappable(const ScriptWrappableVisitor*) const
+
+#define DECLARE_NONVIRTUAL_TRACE_WRAPPABLE_CHILDREN()                      \
+    void traceWrappableChildren(const ScriptWrappableVisitor*) const
+
+
+#define DECLARE_TRACE_WRAPPABLE()                                          \
+    DECLARE_VIRTUAL_TRACE_WRAPPABLE();                                     \
+    DECLARE_VIRTUAL_TRACE_WRAPPABLE_CHILDREN()
+
+#define DEFINE_TRACE_WRAPPABLE(T)                                          \
+    void T::traceWrappable(const ScriptWrappableVisitor* visitor) const    \
+    {                                                                      \
+        if (visitor->isVisited(this))                                      \
+            return;                                                        \
+        visitor->visit(this);                                              \
+        traceWrappableChildren(visitor);                                   \
+    }
+
+#define DECLARE_TRACE_WRAPPABLE_CHILDREN()                                 \
+    void traceWrappableChildren(const ScriptWrappableVisitor*) const override;
+
+#define DEFINE_TRACE_WRAPPABLE_CHILDREN(T)                                 \
+    void T::traceWrappableChildren(const ScriptWrappableVisitor* visitor) const
+
+/**
+ * Visitor able to trace through the script wrappable references. It is used
+ * by the ScriptWrappableHeapTracer during V8 garbage collection.
+ */
+class ScriptWrappableVisitor {

[haraken, 2016/04/13 00:44:01]

It's a bit confusing to mix "trace", "visit", "accept" and "mark". Also it would
be great if we could unify the terms with Oilpan. Oilpan is using "trace" when
visiting an object and "mark" when marking an object.

[Marcel Hlopko, 2016/04/13 08:46:09]

Done

+public:
+    ScriptWrappableVisitor(v8::Isolate* isolate, ScriptWrappableHeapTracer* tracer)
+        : m_isolate(isolate)
+        , m_tracer(tracer)
+        {};
+    void accept(const ScriptWrappable* wrappable) const;
+    void accept(const ScriptWrappable& wrappable) const;
+    void accept(const NodeRareData* rareData) const;
+    bool isVisited(const void* garbageCollected) const;
+    void visit(const ScriptWrappable* scriptWrappable) const;
+    void visit(const void* garbageCollected) const;
+    void visitHandle(v8::Persistent<v8::Object>& handle) const;
+private:
+    v8::Isolate* m_isolate;
+    ScriptWrappableHeapTracer* m_tracer;
+};
+
+}
+#endif