Add a scoping object to help block scripting during plugin destruction.

public/web/WebPluginScriptForbiddenScope.h

+// Copyright 2015 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 WebPluginScriptForbiddenScope_h
+#define WebPluginScriptForbiddenScope_h
+
+#include "public/platform/WebCommon.h"
+
+namespace blink {
+
+class BLINK_EXPORT WebPluginScriptForbiddenScope {
+public:
+    WebPluginScriptForbiddenScope() = delete;
+    static bool isForbidden();
+};
+
+} // namespace blink
+
+#endif // WebPluginScriptForbiddenScope_h