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..7901c785e37f5b25518baaae4f784d3379bff53b
--- /dev/null
+++ b/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.h
@@ -0,0 +1,55 @@
+// 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_WRAPPERS()                                  \

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

Add a comment how to use these macros, or add a link to the
IDLExtendedAttributes.md.

+    virtual void traceWrappers(const ScriptWrappableVisitor*) const
+
+#define DECLARE_NONVIRTUAL_TRACE_WRAPPERS()                               \
+    void traceWrappers(const ScriptWrappableVisitor*) const
+
+#define OVERRIDE_TRACE_WRAPPERS()                                         \

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

Can we unify OVERRIDE_TRACE_WRAPPERS with DECLARE_VIRTUAL_TRACE_WRAPPERS?

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

 oOn 2016/04/13 at 12:26:22, haraken wrote:
Did you mean what I just uploaded, or you meant having only 1 macro for both?

+    void traceWrappers(const ScriptWrappableVisitor*) const override;
+
+#define DEFINE_TRACE_WRAPPERS(T)                                          \
+    void T::traceWrappers(const ScriptWrappableVisitor* visitor) const
+
+/**
+ * Visitor able to trace through the script wrappable references. It is used

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

Visitor is able to

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

Done.

+ * by the ScriptWrappableHeapTracer during V8 garbage collection.
+ */
+class ScriptWrappableVisitor {

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

Add STACK_ALLOCATED.

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

Done.

+public:
+    ScriptWrappableVisitor(v8::Isolate* isolate, ScriptWrappableHeapTracer* tracer)
+        : m_isolate(isolate)
+        , m_tracer(tracer)
+        {};
+    void trace(const ScriptWrappable* wrappable) const;
+    void trace(const ScriptWrappable& wrappable) const;
+    void trace(const NodeRareData* rareData) const;
+    void mark(const ScriptWrappable* scriptWrappable) const;
+    void mark(const void* garbageCollected) const;

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

I'd suggest consistently using "traceWrappers" and "markWrappers" for all these
methods. Then it would be less confusing with Oilpan's ones. (Note that
developers soemtimes need to mix Oilpan's tracing methods and Wrappable's
tracing methods in the same file.)

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

Done.

+    void markHandle(v8::Persistent<v8::Object>& handle) const;
+private:
+    bool isMarked(const void* garbageCollected) const;
+    v8::Isolate* m_isolate;
+    ScriptWrappableHeapTracer* m_tracer;
+};
+
+}
+#endif