Prepare to replicate sandbox flags for OOPIF

public/web/WebSandboxFlags.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 WebSandboxFlags_h
+#define WebSandboxFlags_h
+
+#include "../platform/WebCommon.h"
+
+namespace blink {
+
+// See http://www.whatwg.org/specs/web-apps/current-work/#attr-iframe-sandbox
+// for a list of the sandbox flags.  This enum should be kept in sync with
+// Source/core/dom/SandboxFlags.h.  Enforced in AssertMatchingEnums.cpp
+enum class WebSandboxFlags : int {
+    None = 0,
+    Navigation = 1,
+    Plugins = 1 << 1,
+    Origin = 1 << 2,
+    Forms = 1 << 3,
+    Scripts = 1 << 4,
+    TopNavigation = 1 << 5,
+    Popups = 1 << 6,
+    AutomaticFeatures = 1 << 7,
+    PointerLock = 1 << 8,
+    DocumentDomain = 1 << 9,
+    OrientationLock = 1 << 10,
+    All = -1
+};
+
+} // namespace blink
+
+#endif // WebSandboxFlags_h