Custom Elements: Encapsulates Async and Sync Queues into one class.

Source/core/dom/custom/CustomElementPendingMicrotaskSet.h

+// Copyright 2014 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 CustomElementPendingMicrotaskSet_h
+#define CustomElementPendingMicrotaskSet_h
+
+#include "core/dom/custom/CustomElementAsyncImportMicrotaskQueue.h"
+#include "core/dom/custom/CustomElementSyncMicrotaskQueue.h"
+#include "platform/heap/Handle.h"
+
+namespace WebCore {
+
+class HTMLImportLoader;
+
+class CustomElementPendingMicrotaskSet : public RefCountedWillBeGarbageCollectedFinalized<CustomElementPendingMicrotaskSet> {

[dominicc (has gone to gerrit), 2014/06/18 00:11:28]

This isn't really a "set" in the mathematical or std::set sense of that word.

I think "pending" does not add much here either. The
CustomElementSyncMicrotaskQueue is equally "pending", right? But it does not
have "pending" in the name.

Who uses this? The CustomElementMicrotaskDispatcher; who else?

This is a bad name, but here is a seed of an idea: This is almost like a
priority queue, because the sync stuff goes first.

[Hajime Morrita, 2014/06/18 00:57:05]

Noticed that this is the only object which dispatches microtask steps (besides
the queue itself).
So how about CustomElementMicrotaskStepDispatcher?

+    WTF_MAKE_NONCOPYABLE(CustomElementPendingMicrotaskSet);
+public:
+    static PassRefPtrWillBeRawPtr<CustomElementPendingMicrotaskSet> create() { return adoptRefWillBeNoop(new CustomElementPendingMicrotaskSet()); }
+
+    void enqueue(HTMLImportLoader* parentLoader, PassOwnPtrWillBeRawPtr<CustomElementMicrotaskStep>);
+    void enqueue(HTMLImportLoader* parentLoader, PassOwnPtrWillBeRawPtr<CustomElementMicrotaskImportStep>, bool importIsSync);
+
+    void dispatch();
+    void trace(Visitor*);
+
+#if !defined(NDEBUG)
+    void show(unsigned indent);
+#endif
+
+private:
+    CustomElementPendingMicrotaskSet();
+
+    RefPtrWillBeMember<CustomElementSyncMicrotaskQueue> m_syncQueue;
+    RefPtrWillBeMember<CustomElementAsyncImportMicrotaskQueue> m_asyncQueue;
+};
+
+}
+
+#endif // CustomElementPendingMicrotaskSet_h