Update I420Buffer to new VideoFrameBuffer interface

webrtc/test/video_capturer.cc

 /*
  *  Copyright (c) 2017 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 19 matching lines @@
     // Drop frame in order to respect frame rate constraint.
     return rtc::Optional<VideoFrame>();
   }
 
   rtc::Optional<VideoFrame> out_frame;
   if (out_height != frame.height() || out_width != frame.width()) {
     // Video adapter has requested a down-scale. Allocate a new buffer and
     // return scaled version.
     rtc::scoped_refptr<I420Buffer> scaled_buffer =
         I420Buffer::Create(out_width, out_height);
-    scaled_buffer->ScaleFrom(*frame.video_frame_buffer().get());
+    scaled_buffer->ScaleFrom(*frame.video_frame_buffer()->ToI420());
     out_frame.emplace(
         VideoFrame(scaled_buffer, kVideoRotation_0, frame.timestamp_us()));
   } else {
     // No adaptations needed, just return the frame as is.
     out_frame.emplace(frame);
   }
 
   return out_frame;
 }
 
 void VideoCapturer::AddOrUpdateSink(rtc::VideoSinkInterface<VideoFrame>* sink,
                                     const rtc::VideoSinkWants& wants) {
   video_adapter_->OnResolutionFramerateRequest(
       wants.target_pixel_count, wants.max_pixel_count, wants.max_framerate_fps);
 }
 
 }  // namespace test
 }  // namespace webrtc