iOS: Add new RTCVideoSource interface

webrtc/api/video/i420_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/api/video/i420_buffer.h"
@@ skipping 162 matching lines @@
 }
 int I420Buffer::StrideV() const {
   return stride_v_;
 }
 
 void* I420Buffer::native_handle() const {
   return nullptr;
 }
 
 rtc::scoped_refptr<VideoFrameBuffer> I420Buffer::NativeToI420Buffer() {
-  RTC_NOTREACHED();
-  return nullptr;
+  return this;
 }
 
 uint8_t* I420Buffer::MutableDataY() {
   return const_cast<uint8_t*>(DataY());
 }
 uint8_t* I420Buffer::MutableDataU() {
   return const_cast<uint8_t*>(DataU());
 }
 uint8_t* I420Buffer::MutableDataV() {
   return const_cast<uint8_t*>(DataV());
@@ skipping 56 matching lines @@
       src,
       (src.width() - crop_width) / 2, (src.height() - crop_height) / 2,
       crop_width, crop_height);
 }
 
 void I420Buffer::ScaleFrom(const VideoFrameBuffer& src) {
   CropAndScaleFrom(src, 0, 0, src.width(), src.height());
 }
 
 }  // namespace webrtc