Add a queue for custom element reactions.

third_party/WebKit/Source/core/dom/custom/CustomElementReactionQueue.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 "core/dom/custom/CustomElementReactionQueue.h"
+
+#include "core/dom/custom/CustomElementReaction.h"
+
+namespace blink {
+
+CustomElementReactionQueue::CustomElementReactionQueue()

[yosin_UTC9, 2016/06/01 02:14:01]

Better to use |m_index = 0u| in class declaration and use |= default|

+    : m_index(0u)
+{
+}
+
+CustomElementReactionQueue::~CustomElementReactionQueue()

[yosin_UTC9, 2016/06/01 02:14:01]

nit: = default

+{
+}
+
+DEFINE_TRACE(CustomElementReactionQueue)
+{
+    visitor->trace(m_reactions);
+}
+
+void CustomElementReactionQueue::add(CustomElementReaction* reaction)
+{
+    m_reactions.append(reaction);
+}
+
+// There is one queue per element, so this could be invoked
+// recursively.
+void CustomElementReactionQueue::invokeReactions(Element* element)
+{
+    while (m_index < m_reactions.size()) {
+        CustomElementReaction* reaction = m_reactions[m_index];
+        m_reactions[m_index++] = nullptr;
+        reaction->invoke(element);
+    }
+    // Unlike V0CustomElementsCallbackQueue, reactions are always
+    // inserted by steps which bump the global element queue. This
+    // means we do not need queue "owner" guards.
+    // https://html.spec.whatwg.org/multipage/scripting.html#custom-element-reactions
+    m_index = 0;
+    m_reactions.resize(0);
+}
+
+} // namespace blink