Add separate base classes for I420 and I444 buffers

webrtc/common_video/video_frame_buffer.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.
  */
 #include "webrtc/common_video/include/video_frame_buffer.h"
@@ skipping 78 matching lines @@
       y_stride_(y_stride),
       u_stride_(u_stride),
       v_stride_(v_stride),
       no_longer_used_cb_(no_longer_used) {
 }
 
 WrappedI420Buffer::~WrappedI420Buffer() {
   no_longer_used_cb_();
 }
 
-VideoFrameBuffer::Type WrappedI420Buffer::type() const {
-  return Type::kI420;
-}
-
 int WrappedI420Buffer::width() const {
   return width_;
 }
 
 int WrappedI420Buffer::height() const {
   return height_;
 }
 
 const uint8_t* WrappedI420Buffer::DataY() const {
   return y_plane_;
 }
 const uint8_t* WrappedI420Buffer::DataU() const {
   return u_plane_;
 }
 const uint8_t* WrappedI420Buffer::DataV() const {
   return v_plane_;
 }
 
 int WrappedI420Buffer::StrideY() const {
   return y_stride_;
 }
 int WrappedI420Buffer::StrideU() const {
   return u_stride_;
 }
 int WrappedI420Buffer::StrideV() const {
   return v_stride_;
 }
 
 }  // namespace webrtc