Load CMA backend from shared library

chromecast/public/media/cast_key_system.h

Index: chromecast/public/media/cast_key_system.h
diff --git a/chromecast/public/media/cast_key_system.h b/chromecast/public/media/cast_key_system.h
new file mode 100644
index 0000000000000000000000000000000000000000..d0479462e4382bf10e1cbc10c27a8e2a607c9a29
--- /dev/null
+++ b/chromecast/public/media/cast_key_system.h
@@ -0,0 +1,21 @@
+// 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_SYSTEM_H_
+#define CHROMECAST_PUBLIC_MEDIA_CAST_KEY_SYSTEM_H_
+
+namespace chromecast {
+namespace media {
+
+enum CastKeySystem {
+  KEY_SYSTEM_NONE = 0,
+  KEY_SYSTEM_CLEAR_KEY,
+  KEY_SYSTEM_PLAYREADY,
+  KEY_SYSTEM_WIDEVINE
+};
+
+}  // namespace media
+}  // namespace chromecast
+
+#endif  // CHROMECAST_PUBLIC_MEDIA_CAST_KEY_SYSTEM_H_