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

webrtc/modules/video_coding/generic_decoder.h

 /*
  *  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.
  */
 
@@ skipping 12 matching lines @@
 
 class VCMReceiveCallback;
 
 enum { kDecoderFrameMemoryLength = 10 };
 
 struct VCMFrameInformation {
   int64_t renderTimeMs;
   int64_t decodeStartTimeMs;
   void* userData;
   VideoRotation rotation;
-  VideoContentType content_type;
 };
 
 class VCMDecodedFrameCallback : public DecodedImageCallback {
  public:
   VCMDecodedFrameCallback(VCMTiming* timing, Clock* clock);
   ~VCMDecodedFrameCallback() override;
   void SetUserReceiveCallback(VCMReceiveCallback* receiveCallback);
   VCMReceiveCallback* UserReceiveCallback();
 
   int32_t Decoded(VideoFrame& decodedImage) override;
@@ skipping 59 matching lines @@
   bool PrefersLateDecoding() const;
 
  private:
   VCMDecodedFrameCallback* _callback;
   VCMFrameInformation _frameInfos[kDecoderFrameMemoryLength];
   uint32_t _nextFrameInfoIdx;
   VideoDecoder* const _decoder;
   VideoCodecType _codecType;
   bool _isExternal;
   bool _keyFrameDecoded;
-  VideoContentType _last_keyframe_content_type;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_VIDEO_CODING_GENERIC_DECODER_H_