[Cast] Clean-up: Merge AudioReceiverConfig+VideoReceiverConfig-->FrameReceiverConfig.

media/cast/video_sender/external_video_encoder.cc

Index: media/cast/video_sender/external_video_encoder.cc
diff --git a/media/cast/video_sender/external_video_encoder.cc b/media/cast/video_sender/external_video_encoder.cc
index d2e306504f4357723c28228dfec74834c4cdb125..4a4b5566953dbccc5ee6e2cbfa31c76b146edbcb 100644
--- a/media/cast/video_sender/external_video_encoder.cc
+++ b/media/cast/video_sender/external_video_encoder.cc
@@ -108,6 +108,9 @@ class LocalVideoEncodeAcceleratorClient
       case transport::kFakeSoftwareVideo:
         NOTREACHED() << "Fake software video encoder cannot be external";
         break;
+      case transport::kUnknownVideoCodec:
+        NOTREACHED() << "Video codec not specified";
+        break;
     }
     codec_ = video_config.codec;
     max_frame_rate_ = video_config.max_frame_rate;