Remove lastest_revived_packet from QuicAckFrame since FEC is gone. No functional change expected.

net/quic/quic_framer.cc

Index: net/quic/quic_framer.cc
diff --git a/net/quic/quic_framer.cc b/net/quic/quic_framer.cc
index 042acdc8a82a3ae6adc53cc06d17c1e829c3f6f8..ec849f1cd81c834100be99515645a39eee523c16 100644
--- a/net/quic/quic_framer.cc
+++ b/net/quic/quic_framer.cc
@@ -1384,7 +1384,6 @@ bool QuicFramer::ProcessAckFrame(QuicDataReader* reader,
       set_detailed_error("Unable to read revived packet.");
       return false;
     }
-    ack_frame->latest_revived_packet = revived_packet;
   }
 
   return true;
@@ -1757,9 +1756,6 @@ size_t QuicFramer::GetAckFrameSize(
     ack_size += kNumberOfNackRangesSize + kNumberOfRevivedPacketsSize;
     ack_size += min(ack_info.nack_ranges.size(), kMaxNackRanges) *
                 (missing_packet_number_length + PACKET_1BYTE_PACKET_NUMBER);
-    if (ack.latest_revived_packet != 0) {
-      ack_size += largest_observed_length;
-    }
   }
 
   // In version 23, if the ack will be truncated due to too many nack ranges,
@@ -2048,24 +2044,12 @@ bool QuicFramer::AppendAckFrameAndTypeByte(const QuicPacketHeader& header,
   DCHECK_EQ(num_missing_ranges, num_ranges_written);
 
   // Append revived packets.
-  // If not all the revived packets fit, only mention the ones that do.
-  uint8_t num_revived_packets = frame.latest_revived_packet == 0 ? 0 : 1;
-  if (((writer->capacity() - writer->length()) / largest_observed_length) ==
-      0) {
-    num_revived_packets = 0;
-  }
+  // FEC is not supported.
+  uint8_t num_revived_packets = 0;
   if (!writer->WriteBytes(&num_revived_packets, 1)) {
     return false;
   }
 
-  if (num_revived_packets > 0) {
-    QUIC_BUG_IF(!frame.missing_packets.Contains(frame.latest_revived_packet));
-    if (!AppendPacketSequenceNumber(largest_observed_length,
-                                    frame.latest_revived_packet, writer)) {
-      return false;
-    }
-  }
-
   return true;
 }