VR: Fix HTTP warning staying visible after exiting WebVR.

chrome/browser/android/vr_shell/ui_elements/ui_element_debug_id.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_DEBUG_ID_H_
+#define CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_UI_ELEMENT_DEBUG_ID_H_
+
+namespace vr_shell {
+
+// These identifiers may be used by UI elements to tag themselves for purposes
+// of testing or debugging.
+enum UiElementDebugId {
+  kNone = 0,
+  kWebVrPermanentHttpSecurityWarning,
+  kWebVrTransientHttpSecurityWarning,
+  kCloseButton,
+};
+
+}  // namespace vr_shell
+
+#endif  // CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_UI_ELEMENT_DEBUG_ID_H_