Delete VP8 feedback mode.

webrtc/modules/video_coding/BUILD.gn

Index: webrtc/modules/video_coding/BUILD.gn
diff --git a/webrtc/modules/video_coding/BUILD.gn b/webrtc/modules/video_coding/BUILD.gn
index 1ef5c5d2a6b207787018b8db349d41ca2a5a9588..4240d14ae1a6ea91e5455e1c78215c328cef9e11 100644
--- a/webrtc/modules/video_coding/BUILD.gn
+++ b/webrtc/modules/video_coding/BUILD.gn
@@ -203,8 +203,6 @@ rtc_static_library("webrtc_vp8") {
     "codecs/vp8/include/vp8.h",
     "codecs/vp8/include/vp8_common_types.h",
     "codecs/vp8/realtime_temporal_layers.cc",
-    "codecs/vp8/reference_picture_selection.cc",
-    "codecs/vp8/reference_picture_selection.h",
     "codecs/vp8/screenshare_layers.cc",
     "codecs/vp8/screenshare_layers.h",
     "codecs/vp8/simulcast_encoder_adapter.cc",
@@ -484,7 +482,6 @@ if (rtc_include_tests) {
       "codecs/test/stats_unittest.cc",
       "codecs/test/videoprocessor_unittest.cc",
       "codecs/vp8/default_temporal_layers_unittest.cc",
-      "codecs/vp8/reference_picture_selection_unittest.cc",
       "codecs/vp8/screenshare_layers_unittest.cc",
       "codecs/vp8/simulcast_encoder_adapter_unittest.cc",
       "codecs/vp8/simulcast_unittest.cc",