Remove kVideoCodecUnknown from WebRTC.

There is no difference between how we handle "generic" and "unkown" codecs,
so we don't need to represent both.

Bug: webrtc:8136
Change-Id: I42b0dbc8a0bae67cc21742303c963c8dd5bde1f6
Reviewed-on: https://webrtc-review.googlesource.com/92086
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24316}
diff --git a/modules/video_coding/generic_encoder.cc b/modules/video_coding/generic_encoder.cc
index 7d8bb6a..5cea0a5 100644
--- a/modules/video_coding/generic_encoder.cc
+++ b/modules/video_coding/generic_encoder.cc
@@ -43,7 +43,7 @@
       internal_source_(internal_source),
       encoder_params_({VideoBitrateAllocation(), 0, 0, 0}),
       streams_or_svc_num_(0),
-      codec_type_(VideoCodecType::kVideoCodecUnknown) {}
+      codec_type_(VideoCodecType::kVideoCodecGeneric) {}
 
 VCMGenericEncoder::~VCMGenericEncoder() {}