Remove dead code in vp8_impl files.

webrtc/modules/video_coding/codecs/vp8/simulcast_unittest.h

Index: webrtc/modules/video_coding/codecs/vp8/simulcast_unittest.h
diff --git a/webrtc/modules/video_coding/codecs/vp8/simulcast_unittest.h b/webrtc/modules/video_coding/codecs/vp8/simulcast_unittest.h
index d8e247e26a7563163e0e257d86055015f7035d9d..c82aaa2af2cc768d7acbd82c359303220d65d9f3 100644
--- a/webrtc/modules/video_coding/codecs/vp8/simulcast_unittest.h
+++ b/webrtc/modules/video_coding/codecs/vp8/simulcast_unittest.h
@@ -224,7 +224,6 @@ class TestVp8Simulcast : public ::testing::Test {
     settings->VP8()->denoisingOn = true;
     settings->VP8()->errorConcealmentOn = false;
     settings->VP8()->automaticResizeOn = false;
-    settings->VP8()->feedbackModeOn = false;
     settings->VP8()->frameDroppingOn = true;
     settings->VP8()->keyFrameInterval = 3000;
   }