Save width/height of SPS nalus and restore them on the first packet of an IDR.

webrtc/modules/video_coding/h264_sps_pps_tracker.h

 /*
  *  Copyright (c) 2016 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 24 matching lines @@
 
  private:
   struct PpsInfo {
     int sps_id = -1;
     size_t size = 0;
     std::unique_ptr<uint8_t[]> data;
   };
 
   struct SpsInfo {
     size_t size = 0;
+    int width = -1;
+    int height = -1;
     std::unique_ptr<uint8_t[]> data;
   };
 
   std::map<uint32_t, PpsInfo> pps_data_;
   std::map<uint32_t, SpsInfo> sps_data_;
 };
 
 }  // namespace video_coding
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_VIDEO_CODING_H264_SPS_PPS_TRACKER_H_