Fix a bug where the packet was put into unacked packets when it was

net/quic/quic_sent_packet_manager.cc

Index: net/quic/quic_sent_packet_manager.cc
diff --git a/net/quic/quic_sent_packet_manager.cc b/net/quic/quic_sent_packet_manager.cc
index a25cb5e6c9f4a16c07ad0666f4541ef7652d6ef7..04c5ce1127ed08c6efd1c222010d0ba0521ce2f6 100644
--- a/net/quic/quic_sent_packet_manager.cc
+++ b/net/quic/quic_sent_packet_manager.cc
@@ -302,15 +302,9 @@ void QuicSentPacketManager::RetransmitUnackedPackets(
        unacked_it != unacked_packets_.end(); ++unacked_it) {
     const RetransmittableFrames* frames =
         unacked_it->second.retransmittable_frames;
-    if (frames == NULL) {
-      continue;
-    }
     if (retransmission_type == ALL_PACKETS ||
-        frames->encryption_level() == ENCRYPTION_INITIAL) {
-      // TODO(satyamshekhar): Think about congestion control here.
-      // Specifically, about the retransmission count of packets being sent
-      // proactively to achieve 0 (minimal) RTT.
-      if (unacked_it->second.retransmittable_frames) {
+        (frames != NULL && frames->encryption_level() == ENCRYPTION_INITIAL)) {
+      if (frames) {
         OnPacketAbandoned(unacked_it);
         MarkForRetransmission(unacked_it->first, NACK_RETRANSMISSION);
       } else {
@@ -548,18 +542,13 @@ bool QuicSentPacketManager::OnPacketSent(
     TransmissionType transmission_type,
     HasRetransmittableData has_retransmittable_data) {
   DCHECK_LT(0u, sequence_number);
-  // In some edge cases, on some platforms (such as Windows), it is possible
-  // that we were write-blocked when we tried to send a packet, and then decided
-  // not to send the packet (such as when the encryption key changes, and we
-  // "discard" the unsent packet).  In that rare case, we may indeed
-  // asynchronously (later) send the packet, calling this method, but the
-  // sequence number may already be erased from unacked_packets_ map. In that
-  // case, we can just return false since the packet will not be tracked for
-  // retransmission.
-  if (!ContainsKey(unacked_packets_, sequence_number))
-    return false;
-  DCHECK(!unacked_packets_[sequence_number].pending);
   UnackedPacketMap::iterator it = unacked_packets_.find(sequence_number);
+  // In rare circumstances, the packet could be serialized, sent, and then acked
+  // before OnPacketSent is called.
+  if (it == unacked_packets_.end()) {
+    return false;
+  }
+  DCHECK(!it->second.pending);
 
   // Only track packets the send algorithm wants us to track.
   if (!send_algorithm_->OnPacketSent(sent_time, sequence_number, bytes,