[Experiment] Alpha Channel Support

examples/unityplugin/video_observer.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.
  */
 
 #include "examples/unityplugin/video_observer.h"
 
 void VideoObserver::SetVideoCallback(I420FRAMEREADY_CALLBACK callback) {
   std::lock_guard<std::mutex> lock(mutex);
   OnI420FrameReady = callback;
 }
 
 void VideoObserver::OnFrame(const webrtc::VideoFrame& frame) {
   std::unique_lock<std::mutex> lock(mutex);
-  rtc::scoped_refptr<webrtc::PlanarYuvBuffer> buffer(
+  rtc::scoped_refptr<webrtc::I420BufferInterface> buffer(
       frame.video_frame_buffer()->ToI420());
   if (OnI420FrameReady) {
     OnI420FrameReady(buffer->DataY(), buffer->DataU(), buffer->DataV(),
-                     buffer->StrideY(), buffer->StrideU(), buffer->StrideV(),
-                     frame.width(), frame.height());
+                     buffer->DataA(), buffer->StrideY(), buffer->StrideU(),
+                     buffer->StrideV(), buffer->StrideA(), frame.width(),
+                     frame.height());
   }
 }