VR: Fix HTTP warning staying visible after exiting WebVR.

chrome/browser/android/vr_shell/ui_elements/ui_element_identifiers.h

+// Copyright 2017 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_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_UI_ELEMENT_IDENTIFIERS_H_
+#define CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_UI_ELEMENT_IDENTIFIERS_H_
+
+namespace vr_shell {
+
+// This class manages the communication of browser state from VR shell to the
+// HTML UI. State information is asynchronous and unidirectional.
+enum UiElementIdentifier {
+  kNone = 0,
+  kWebVrPermanentHttpSecurityWarning,
+  kWebVrTransientHttpSecurityWarning,
+};
+
+}  // namespace vr_shell
+
+#endif  // CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_UI_ELEMENT_IDENTIFIERS_H_