[Chromecast] Allow CMA backend to notify of key expiry

chromecast/public/media/media_pipeline_backend.h

Index: chromecast/public/media/media_pipeline_backend.h
diff --git a/chromecast/public/media/media_pipeline_backend.h b/chromecast/public/media/media_pipeline_backend.h
index 6c2b286371a33dfcc9f21d48dd268a8f62525e37..ece8452a33b6f09ab31491d69e5fa7e8a4cc1f91 100644
--- a/chromecast/public/media/media_pipeline_backend.h
+++ b/chromecast/public/media/media_pipeline_backend.h
@@ -5,6 +5,10 @@
 #ifndef CHROMECAST_PUBLIC_MEDIA_MEDIA_PIPELINE_BACKEND_H_
 #define CHROMECAST_PUBLIC_MEDIA_MEDIA_PIPELINE_BACKEND_H_
 
+#include <stdint.h>
+#include <string>
+
+#include "cast_key_status.h"
 #include "decoder_config.h"
 
 namespace chromecast {
@@ -142,6 +146,11 @@ class MediaPipelineBackend {
     // will be made after this is called.
     virtual void OnDecoderError(Decoder* decoder) = 0;
 
+    // Must be called when a decryption key status changes.
+    virtual void OnKeyStatusChanged(const std::string& key_id,
+                                    CastKeyStatus key_status,
+                                    uint32_t system_code) = 0;
+
    protected:
     virtual ~Delegate() {}
   };