[vr] Bail on unhandled code points.

chrome/browser/android/vr_shell/ui_unsupported_mode.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_UNSUPPORTED_MODE_H_
+#define CHROME_BROWSER_ANDROID_VR_SHELL_UI_UNSUPPORTED_MODE_H_
+
+namespace vr_shell {
+
+// Ensure that this stays in sync with VRUnsupportedMode in enums.xml
+// These values are written to logs.  New enum values can be added, but existing
+// enums must never be renumbered or deleted and reused.
+enum class UiUnsupportedMode : int {
+  kUnhandledCodePoint = 0,
+
+  // This must be last.
+  kCount,
+};
+
+}  // namespace vr_shell
+
+#endif  // CHROME_BROWSER_ANDROID_VR_SHELL_UI_UNSUPPORTED_MODE_H_