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

webrtc/modules/video_coding/packet_buffer.cc

Index: webrtc/modules/video_coding/packet_buffer.cc
diff --git a/webrtc/modules/video_coding/packet_buffer.cc b/webrtc/modules/video_coding/packet_buffer.cc
index 7b01e4cb274bb720fcc085ab08c063e971e1fd71..452e762b9f10c5c41392e81bf95531124da95e8e 100644
--- a/webrtc/modules/video_coding/packet_buffer.cc
+++ b/webrtc/modules/video_coding/packet_buffer.cc
@@ -40,7 +40,6 @@ PacketBuffer::PacketBuffer(Clock* clock,
       size_(start_buffer_size),
       max_size_(max_buffer_size),
       first_seq_num_(0),
-      last_seq_num_(0),
       first_packet_received_(false),
       is_cleared_to_first_seq_num_(false),
       data_buffer_(start_buffer_size),
@@ -65,7 +64,6 @@ bool PacketBuffer::InsertPacket(VCMPacket* packet) {
 
     if (!first_packet_received_) {
       first_seq_num_ = seq_num;
-      last_seq_num_ = seq_num;
       first_packet_received_ = true;
     } else if (AheadOf(first_seq_num_, seq_num)) {
       // If we have explicitly cleared past this packet then it's old,
@@ -100,9 +98,6 @@ bool PacketBuffer::InsertPacket(VCMPacket* packet) {
       }
     }
 
-    if (AheadOf(seq_num, last_seq_num_))
-      last_seq_num_ = seq_num;
-
     sequence_buffer_[index].frame_begin = packet->is_first_packet_in_frame;
     sequence_buffer_[index].frame_end = packet->markerBit;
     sequence_buffer_[index].seq_num = packet->seqNum;
@@ -186,6 +181,8 @@ bool PacketBuffer::PotentialNewFrame(uint16_t seq_num) const {
     return true;
   if (!sequence_buffer_[prev_index].used)
     return false;
+  if (sequence_buffer_[prev_index].frame_created)
+    return false;
   if (sequence_buffer_[prev_index].seq_num !=
       static_cast<uint16_t>(sequence_buffer_[index].seq_num - 1)) {
     return false;