Upgrade in-document custom elements when an element is defined.

third_party/WebKit/Source/core/dom/custom/CEReactionsScope.h

Index: third_party/WebKit/Source/core/dom/custom/CEReactionsScope.h
diff --git a/third_party/WebKit/Source/core/dom/custom/CEReactionsScope.h b/third_party/WebKit/Source/core/dom/custom/CEReactionsScope.h
new file mode 100644
index 0000000000000000000000000000000000000000..32858505e631e5d5676d3130c82da7e2680359f6
--- /dev/null
+++ b/third_party/WebKit/Source/core/dom/custom/CEReactionsScope.h
@@ -0,0 +1,60 @@
+// 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 CEReactionsScope_h
+#define CEReactionsScope_h
+
+#include "core/CoreExport.h"
+#include "platform/heap/Handle.h"
+#include "wtf/Allocator.h"
+#include "wtf/StdLibExtras.h"
+
+namespace blink {
+
+class CustomElementReaction;
+class Element;
+class FrameHost;
+
+// https://html.spec.whatwg.org/multipage/scripting.html#cereactions
+class CORE_EXPORT CEReactionsScope final {
+    STACK_ALLOCATED();
+    DISALLOW_COPY_AND_ASSIGN(CEReactionsScope);
+public:
+    static CEReactionsScope* current()
+    {
+        return topOfStack();
+    }
+
+    CEReactionsScope()
+        : m_prev(topOfStack())
+    {
+        topOfStack() = this;
+    }
+
+    ~CEReactionsScope()
+    {
+        CEReactionsScope** top = &topOfStack();
+        *top = (*top)->m_prev;
+        if (m_frameHost.get())
+            invokeReactions();
+    }
+
+    void enqueue(Element*, CustomElementReaction*);
+
+private:
+    static CEReactionsScope*& topOfStack()
+    {
+        static CEReactionsScope* top = nullptr;
+        return top;
+    }
+
+    void invokeReactions();
+
+    CEReactionsScope* m_prev;
+    Member<FrameHost> m_frameHost;
+};
+
+} // namespace blink
+
+#endif // CEReactionsScope_h