Enable shadow DOM-based "missing plugin" placeholder.

chrome/renderer/plugins/shadow_dom_plugin_placeholder.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 CHROME_RENDERER_PLUGINS_SHADOW_DOM_PLUGIN_PLACEHOLDER_H_
+#define CHROME_RENDERER_PLUGINS_SHADOW_DOM_PLUGIN_PLACEHOLDER_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "third_party/WebKit/public/web/WebPluginPlaceholder.h"
+
+// This is the Chrome implementation of shadow DOM plugin placeholders,
+// intended to ultimately replace those based on WebViewPlugin.
+// It is guarded by the --enable-plugin-placeholder-shadow-dom switch.
+
+// Returns |true| if shadow DOM plugin placeholders are enabled.
+bool ShadowDOMPluginPlaceholderEnabled();
+
+// Creates a placeholder suitable for representing a missing plugin.
+scoped_ptr<blink::WebPluginPlaceholder>
+CreateShadowDOMPlaceholderForMissingPlugin();
+
+// For testing, these recognize the type of plugin that was produced,
+// assuming it was produced by a function in this header.
+bool IsShadowDOMPlaceholderForMissingPlugin(
+    blink::WebPluginPlaceholder* placeholder);
+
+#endif  // CHROME_RENDERER_PLUGINS_SHADOW_DOM_PLUGIN_PLACEHOLDER_H_