Delete unused enum StreamType and kViEStreamType* values.

Unused since https://codereview.webrtc.org/1693553002
Also drop an unneeded include of video_stream_decoder.h.

Bug: webrtc:7408
Change-Id: I249ecfe41b55b59abbd2e880ef144d64f130b0b0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/128767
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27242}
diff --git a/video/receive_statistics_proxy.h b/video/receive_statistics_proxy.h
index e1a0784..723dc27 100644
--- a/video/receive_statistics_proxy.h
+++ b/video/receive_statistics_proxy.h
@@ -31,7 +31,6 @@
 #include "video/report_block_stats.h"
 #include "video/stats_counter.h"
 #include "video/video_quality_observer.h"
-#include "video/video_stream_decoder.h"
 
 namespace webrtc {
 
diff --git a/video/video_stream_decoder.h b/video/video_stream_decoder.h
index 54554eb..b029407 100644
--- a/video/video_stream_decoder.h
+++ b/video/video_stream_decoder.h
@@ -31,11 +31,6 @@
 class VideoReceiver;
 }  // namespace vcm
 
-enum StreamType {
-  kViEStreamTypeNormal = 0,  // Normal media stream
-  kViEStreamTypeRtx = 1      // Retransmission media stream
-};
-
 class VideoStreamDecoder : public VCMReceiveCallback,
                            public VCMReceiveStatisticsCallback {
  public: