Introduce infrastructure for tracing ScriptWrappables.

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 "bindings/core/v8/ScriptWrappable.h"
 #include "wtf/HashSet.h"
 #include "wtf/ThreadSpecific.h"
 #include "wtf/Threading.h"
 
 namespace blink {
 
 namespace {
 
 using ActiveScriptWrappableSetType = HashSet<const ActiveScriptWrappable*>;
 
@@ skipping 14 matching lines @@
 ActiveScriptWrappable::~ActiveScriptWrappable()
 {
     activeScriptWrappables().remove(this);
 }
 
 ScriptWrappable* ActiveScriptWrappable::toScriptWrappable() const
 {
     return m_scriptWrappable;
 }
 
+void ActiveScriptWrappable::traceActiveScriptWrappables(ScriptWrappableVisitor* visitor)
+{
+    for (auto activeWrappable : activeScriptWrappables()) {
+        if (!activeWrappable->hasPendingActivity())
+            continue;
+
+        visitor->traceWrappers(activeWrappable->toScriptWrappable());
+    }
+}
+
 } // namespace blink