Widevine MediaCas client code that works with Android R

oemcrypto/ref/src/keys.cpp

@@ -0,0 +1,10 @@
+// If you are using a baked-in certificate instead of supporting keyboxes,
+// you should have received a keys.cpp from Widevine that replaces this file.
+//
+// If you are not using a baked-in certificate, then you may ignore this file,
+// as it intentionally defines an empty key.
+
+#include "keys.h"
+
+const uint8_t kPrivateKey[] = { 0, };
+const size_t kPrivateKeySize = 0;