Added is_last_packet_in_frame to match is_first_packet_in_frame.

Today we use |is_first_packet_in_frame| to know when a frame begins and the
|markerBit| to know when it ends, but the markerbit does not actually mark the
end of a frame, it marks the end of a picture.

Bug: webrtc:9361
Change-Id: Icc70e6075590cdc31e875a4eb9d489868adbb67c
Reviewed-on: https://webrtc-review.googlesource.com/100160
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24722}
diff --git a/modules/rtp_rtcp/source/rtp_video_header.h b/modules/rtp_rtcp/source/rtp_video_header.h
index 68b4884..288b7d0 100644
--- a/modules/rtp_rtcp/source/rtp_video_header.h
+++ b/modules/rtp_rtcp/source/rtp_video_header.h
@@ -52,6 +52,7 @@
   VideoRotation rotation = VideoRotation::kVideoRotation_0;
   VideoContentType content_type = VideoContentType::UNSPECIFIED;
   bool is_first_packet_in_frame = false;
+  bool is_last_packet_in_frame = false;
   uint8_t simulcastIdx = 0;
   VideoCodecType codec = VideoCodecType::kVideoCodecGeneric;