[Chromecast] Allow CMA backend to notify of key expiry

chromecast/public/media/cast_key_status.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 CHROMECAST_PUBLIC_MEDIA_CAST_KEY_STATUS_H_
+#define CHROMECAST_PUBLIC_MEDIA_CAST_KEY_STATUS_H_
+
+namespace chromecast {
+namespace media {
+
+// Status of encryption key.  See EME spec for details:
+// https://w3c.github.io/encrypted-media/  - not all key status values
+// are supported currently.
+enum CastKeyStatus { KEY_STATUS_USABLE = 0, KEY_STATUS_EXPIRED };
+
+}  // namespace media
+}  // namespace chromecast
+
+#endif  // CHROMECAST_PUBLIC_MEDIA_CAST_KEY_STATUS_H_