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

Index: webrtc/modules/video_coding/h264_sps_pps_tracker.h
diff --git a/webrtc/modules/video_coding/h264_sps_pps_tracker.h b/webrtc/modules/video_coding/h264_sps_pps_tracker.h
index e7692687794ad88192ec23edc9b4658eed3e6255..7f8bc04416f63656fb99623975681cbc9df8114e 100644
--- a/webrtc/modules/video_coding/h264_sps_pps_tracker.h
+++ b/webrtc/modules/video_coding/h264_sps_pps_tracker.h
@@ -42,6 +42,8 @@ class H264SpsPpsTracker {
 
   struct SpsInfo {
     size_t size = 0;
+    int width = -1;
+    int height = -1;
     std::unique_ptr<uint8_t[]> data;
   };