Add content type information to encoded images and corresponding rtp extension header

webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc

 /*
  *  Copyright (c) 2014 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 688 matching lines @@
   RTC_DCHECK_LE(encoded_image_._length, encoded_image_._size);
 
   CodecSpecificInfo codec_specific;
   PopulateCodecSpecific(&codec_specific, *pkt, input_image_->timestamp());
 
   if (encoded_image_._length > 0) {
     TRACE_COUNTER1("webrtc", "EncodedFrameSize", encoded_image_._length);
     encoded_image_._timeStamp = input_image_->timestamp();
     encoded_image_.capture_time_ms_ = input_image_->render_time_ms();
     encoded_image_.rotation_ = input_image_->rotation();
+    if (codec_.mode == kScreensharing)
+      encoded_image_.content_type_ = VideoContentType::kScreenshare;
+    else
+      encoded_image_.content_type_ = VideoContentType::kUnspecified;
     encoded_image_._encodedHeight = raw_->d_h;
     encoded_image_._encodedWidth = raw_->d_w;
     int qp = -1;
     vpx_codec_control(encoder_, VP8E_GET_LAST_QUANTIZER, &qp);
     encoded_image_.qp_ = qp;
     encoded_complete_callback_->OnEncodedImage(encoded_image_, &codec_specific,
                                                &frag_info);
   }
   return WEBRTC_VIDEO_CODEC_OK;
 }
@@ skipping 286 matching lines @@
   frame_buffer_pool_.ClearPool();
   inited_ = false;
   return WEBRTC_VIDEO_CODEC_OK;
 }
 
 const char* VP9DecoderImpl::ImplementationName() const {
   return "libvpx";
 }
 
 }  // namespace webrtc