Remove no-op VideoDecoder::Reset implementation.

webrtc/video/video_decoder.cc

 /*
  *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 150 matching lines @@
     DecodedImageCallback* callback) {
   LOG(LS_ERROR)
       << "Can't register decode complete callback on NullVideoDecoder.";
   return WEBRTC_VIDEO_CODEC_OK;
 }
 
 int32_t NullVideoDecoder::Release() {
   return WEBRTC_VIDEO_CODEC_OK;
 }
 
-int32_t NullVideoDecoder::Reset() {
-  return WEBRTC_VIDEO_CODEC_OK;
-}
-
 const char* NullVideoDecoder::ImplementationName() const {
   return "NullVideoDecoder";
 }
 
 }  // namespace webrtc