Piggybacking simulcast id and ALR experiment id into video content type extension.

webrtc/test/fake_encoder.cc

 /*
  *  Copyright (c) 2013 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 133 matching lines @@
     std::unique_ptr<uint8_t[]> encoded_buffer(new uint8_t[num_encoded_bytes]);
     memcpy(encoded_buffer.get(), encoded_buffer_, num_encoded_bytes);
     EncodedImage encoded(encoded_buffer.get(), stream_bytes, num_encoded_bytes);
     encoded._timeStamp = input_image.timestamp();
     encoded.capture_time_ms_ = input_image.render_time_ms();
     encoded._frameType = (*frame_types)[i];
     encoded._encodedWidth = simulcast_streams[i].width;
     encoded._encodedHeight = simulcast_streams[i].height;
     encoded.rotation_ = input_image.rotation();
     encoded.content_type_ = (mode == kScreensharing)
-                                ? VideoContentType::SCREENSHARE
-                                : VideoContentType::UNSPECIFIED;
+                                ? VideoContentType::Screenshare()
+                                : VideoContentType::Unspecified();
     specifics.codec_name = ImplementationName();
     specifics.codecSpecific.generic.simulcast_idx = i;
     RTC_DCHECK(callback);
     if (callback->OnEncodedImage(encoded, &specifics, nullptr).error !=
         EncodedImageCallback::Result::OK) {
       return -1;
     }
     bits_available -= std::min(encoded._length * 8, bits_available);
   }
   return 0;
@@ skipping 202 matching lines @@
   RTC_DCHECK_CALLED_SEQUENTIALLY(&sequence_checker_);
 
   queue1_.reset();
   queue2_.reset();
 
   return FakeH264Encoder::Release();
 }
 
 }  // namespace test
 }  // namespace webrtc