Don't detect a new frame if a previous packet is used in a previous frame.

webrtc/modules/video_coding/packet_buffer.h

Index: webrtc/modules/video_coding/packet_buffer.h
diff --git a/webrtc/modules/video_coding/packet_buffer.h b/webrtc/modules/video_coding/packet_buffer.h
index da7e80ffaa81d0e310d1587cdafb2877c183c674..001f8bd89de928bb31a14c490a2efe5df3fd8c7a 100644
--- a/webrtc/modules/video_coding/packet_buffer.h
+++ b/webrtc/modules/video_coding/packet_buffer.h
@@ -126,9 +126,6 @@ class PacketBuffer {
   // The fist sequence number currently in the buffer.
   uint16_t first_seq_num_ GUARDED_BY(crit_);
 
-  // The last sequence number currently in the buffer.
-  uint16_t last_seq_num_ GUARDED_BY(crit_);
-
   // If the packet buffer has received its first packet.
   bool first_packet_received_ GUARDED_BY(crit_);