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 c577f4f6b84ca9f9c8e99f3201637fc7fb9c270a..c6cbfca009d7400f9a7b4d8988535e1038fb08e4 100644
--- a/webrtc/modules/video_coding/BUILD.gn
+++ b/webrtc/modules/video_coding/BUILD.gn
@@ -202,8 +202,6 @@ rtc_static_library("webrtc_vp8") {
     "codecs/vp8/default_temporal_layers.h",
     "codecs/vp8/include/vp8.h",
     "codecs/vp8/include/vp8_common_types.h",
-    "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",
@@ -483,7 +481,6 @@ 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",