[v8 gc] Introduce a base class for all objects that can have pending activity

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

+// 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/ActiveScriptWrappable.h"
+
+#include "wtf/HashSet.h"
+#include "wtf/ThreadSpecific.h"
+#include "wtf/Threading.h"
+
+namespace blink {
+
+namespace {
+
+using ActiveScriptWrappableSetType = HashSet<const ActiveScriptWrappable*>;
+
+ActiveScriptWrappableSetType& activeScriptWrappables()
+{
+    DEFINE_THREAD_SAFE_STATIC_LOCAL(ThreadSpecific<ActiveScriptWrappableSetType>, activeScriptWrappableSet, new ThreadSpecific<ActiveScriptWrappableSetType>());
+    return *activeScriptWrappableSet;
+}
+
+} // namespace
+
+ActiveScriptWrappable::ActiveScriptWrappable(ScriptWrappable* self)
+    : m_scriptWrappable(self)
+{
+    activeScriptWrappables().add(this);
+}
+
+ActiveScriptWrappable::~ActiveScriptWrappable()

[sof, 2016/05/10 05:22:26]

haraken@: is it guaranteed that this global set of bare pointers never contain
anything that's about to be (lazily) swept, and will not be visited when tracing
ScriptWrappables?

+{
+    activeScriptWrappables().remove(this);
+}
+
+ScriptWrappable* ActiveScriptWrappable::toScriptWrappable() const
+{
+    return m_scriptWrappable;
+}
+
+} // namespace blink