Revert of Delete VideoFrame default constructor, and IsZeroSize method.

webrtc/common_video/video_frame.cc

 /*
  *  Copyright (c) 2012 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/video_frame.h"
 
 #include <string.h>
 
 #include <algorithm>  // swap
 
 #include "webrtc/base/bind.h"
 #include "webrtc/base/checks.h"
 
 namespace webrtc {
 
 // FFmpeg's decoder, used by H264DecoderImpl, requires up to 8 bytes padding due
 // to optimized bitstream readers. See avcodec_decode_video2.
 const size_t EncodedImage::kBufferPaddingBytesH264 = 8;
 
+VideoFrame::VideoFrame()
+    : video_frame_buffer_(nullptr),
+      timestamp_rtp_(0),
+      ntp_time_ms_(0),
+      timestamp_us_(0),
+      rotation_(kVideoRotation_0) {}
+
 VideoFrame::VideoFrame(const rtc::scoped_refptr<VideoFrameBuffer>& buffer,
                        webrtc::VideoRotation rotation,
                        int64_t timestamp_us)
     : video_frame_buffer_(buffer),
       timestamp_rtp_(0),
       ntp_time_ms_(0),
       timestamp_us_(timestamp_us),
       rotation_(rotation) {}
 
 VideoFrame::VideoFrame(const rtc::scoped_refptr<VideoFrameBuffer>& buffer,
                        uint32_t timestamp,
                        int64_t render_time_ms,
                        VideoRotation rotation)
     : video_frame_buffer_(buffer),
       timestamp_rtp_(timestamp),
       ntp_time_ms_(0),
       timestamp_us_(render_time_ms * rtc::kNumMicrosecsPerMillisec),
       rotation_(rotation) {
   RTC_DCHECK(buffer);
 }
 
 int VideoFrame::width() const {
   return video_frame_buffer_ ? video_frame_buffer_->width() : 0;
 }
 
 int VideoFrame::height() const {
   return video_frame_buffer_ ? video_frame_buffer_->height() : 0;
 }
 
+bool VideoFrame::IsZeroSize() const {
+  return !video_frame_buffer_;
+}
+
 rtc::scoped_refptr<VideoFrameBuffer> VideoFrame::video_frame_buffer() const {
   return video_frame_buffer_;
 }
 
 size_t EncodedImage::GetBufferPaddingBytes(VideoCodecType codec_type) {
   switch (codec_type) {
     case kVideoCodecVP8:
     case kVideoCodecVP9:
       return 0;
     case kVideoCodecH264:
       return kBufferPaddingBytesH264;
     case kVideoCodecI420:
     case kVideoCodecRED:
     case kVideoCodecULPFEC:
     case kVideoCodecFlexfec:
     case kVideoCodecGeneric:
     case kVideoCodecUnknown:
       return 0;
   }
   RTC_NOTREACHED();
   return 0;
 }
 
 }  // namespace webrtc