Add a custom element to own structure of shadow DOM plugin placeholders.

Source/core/html/shadow/PluginPlaceholderElement.cpp

Index: Source/core/html/shadow/PluginPlaceholderElement.cpp
diff --git a/Source/core/html/shadow/PluginPlaceholderElement.cpp b/Source/core/html/shadow/PluginPlaceholderElement.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..e5f63790b70b7d869c6a51d0ecd57b9a51a219d0
--- /dev/null
+++ b/Source/core/html/shadow/PluginPlaceholderElement.cpp
@@ -0,0 +1,33 @@
+// 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.
+
+#include "config.h"
+#include "core/html/shadow/PluginPlaceholderElement.h"
+
+#include "bindings/core/v8/V8PluginPlaceholderElement.h"
+#include "core/dom/Document.h"
+#include "wtf/Assertions.h"
+
+namespace blink {
+
+PluginPlaceholderElement::PluginPlaceholderElement(Document& document)
+    : HTMLDivElement(document)
+{
+}
+
+PassRefPtrWillBeRawPtr<PluginPlaceholderElement> PluginPlaceholderElement::create(Document& document)
+{
+    RefPtrWillBeRawPtr<PluginPlaceholderElement> element = adoptRefWillBeNoop(new PluginPlaceholderElement(document));
+    bool success = V8PluginPlaceholderElement::PrivateScript::createdCallbackMethod(document.frame(), element.get());
+    ASSERT_UNUSED(success, success);
+    return element.release();
+}
+
+void PluginPlaceholderElement::setMessage(const String& message)
+{
+    bool success = V8PluginPlaceholderElement::PrivateScript::messageAttributeSetter(document().frame(), this, message);
+    ASSERT_UNUSED(success, success);
+}
+
+} // namespace blink