diff --git a/quic/core/quic_transmission_info.h b/quic/core/quic_transmission_info.h
new file mode 100644
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+++ b/quic/core/quic_transmission_info.h
@@ -0,0 +1,67 @@
+// Copyright (c) 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef QUICHE_QUIC_CORE_QUIC_TRANSMISSION_INFO_H_
+#define QUICHE_QUIC_CORE_QUIC_TRANSMISSION_INFO_H_
+
+#include <list>
+
+#include "net/third_party/quiche/src/quic/core/frames/quic_frame.h"
+#include "net/third_party/quiche/src/quic/core/quic_ack_listener_interface.h"
+#include "net/third_party/quiche/src/quic/core/quic_types.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_export.h"
+
+namespace quic {
+
+// Stores details of a single sent packet.
+struct QUIC_EXPORT_PRIVATE QuicTransmissionInfo {
+  // Used by STL when assigning into a map.
+  QuicTransmissionInfo();
+
+  // Constructs a Transmission with a new all_transmissions set
+  // containing |packet_number|.
+  QuicTransmissionInfo(EncryptionLevel level,
+                       QuicPacketNumberLength packet_number_length,
+                       TransmissionType transmission_type,
+                       QuicTime sent_time,
+                       QuicPacketLength bytes_sent,
+                       bool has_crypto_handshake,
+                       int num_padding_bytes);
+
+  QuicTransmissionInfo(const QuicTransmissionInfo& other);
+
+  ~QuicTransmissionInfo();
+
+  QuicFrames retransmittable_frames;
+  EncryptionLevel encryption_level;
+  QuicPacketNumberLength packet_number_length;
+  QuicPacketLength bytes_sent;
+  QuicTime sent_time;
+  // Reason why this packet was transmitted.
+  TransmissionType transmission_type;
+  // In flight packets have not been abandoned or lost.
+  bool in_flight;
+  // State of this packet.
+  SentPacketState state;
+  // True if the packet contains stream data from the crypto stream.
+  bool has_crypto_handshake;
+  // Non-zero if the packet needs padding if it's retransmitted.
+  int16_t num_padding_bytes;
+  // Stores the packet number of the next retransmission of this packet.
+  // Zero if the packet has not been retransmitted.
+  // TODO(fayang): rename this to first_sent_after_loss_ when deprecating
+  // QUIC_VERSION_41.
+  QuicPacketNumber retransmission;
+  // The largest_acked in the ack frame, if the packet contains an ack.
+  QuicPacketNumber largest_acked;
+};
+// TODO(ianswett): Add static_assert when size of this struct is reduced below
+// 64 bytes.
+// NOTE(vlovich): Existing static_assert removed because padding differences on
+// 64-bit iOS resulted in an 88-byte struct that is greater than the 84-byte
+// limit on other platforms.  Removing per ianswett's request.
+
+}  // namespace quic
+
+#endif  // QUICHE_QUIC_CORE_QUIC_TRANSMISSION_INFO_H_