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diff --git a/third_party/libwebrtc/net/dcsctp/rx/reassembly_streams.h b/third_party/libwebrtc/net/dcsctp/rx/reassembly_streams.h
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+++ b/third_party/libwebrtc/net/dcsctp/rx/reassembly_streams.h
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+/*
+ *  Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef NET_DCSCTP_RX_REASSEMBLY_STREAMS_H_
+#define NET_DCSCTP_RX_REASSEMBLY_STREAMS_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <functional>
+#include <vector>
+
+#include "absl/strings/string_view.h"
+#include "api/array_view.h"
+#include "net/dcsctp/common/sequence_numbers.h"
+#include "net/dcsctp/packet/chunk/forward_tsn_common.h"
+#include "net/dcsctp/packet/data.h"
+#include "net/dcsctp/public/dcsctp_handover_state.h"
+#include "net/dcsctp/public/dcsctp_message.h"
+
+namespace dcsctp {
+
+// Implementations of this interface will be called when data is received, when
+// data should be skipped/forgotten or when sequence number should be reset.
+//
+// As a result of these operations - mainly when data is received - the
+// implementations of this interface should notify when a message has been
+// assembled, by calling the provided callback of type `OnAssembledMessage`. How
+// it assembles messages will depend on e.g. if a message was sent on an ordered
+// or unordered stream.
+//
+// Implementations will - for each operation - indicate how much additional
+// memory that has been used as a result of performing the operation. This is
+// used to limit the maximum amount of memory used, to prevent out-of-memory
+// situations.
+class ReassemblyStreams {
+ public:
+  // This callback will be provided as an argument to the constructor of the
+  // concrete class implementing this interface and should be called when a
+  // message has been assembled as well as indicating from which TSNs this
+  // message was assembled from.
+  using OnAssembledMessage =
+      std::function<void(rtc::ArrayView<const UnwrappedTSN> tsns,
+                         DcSctpMessage message)>;
+
+  virtual ~ReassemblyStreams() = default;
+
+  // Adds a data chunk to a stream as identified in `data`.
+  // If it was the last remaining chunk in a message, reassemble one (or
+  // several, in case of ordered chunks) messages.
+  //
+  // Returns the additional number of bytes added to the queue as a result of
+  // performing this operation. If this addition resulted in messages being
+  // assembled and delivered, this may be negative.
+  virtual int Add(UnwrappedTSN tsn, Data data) = 0;
+
+  // Called for incoming FORWARD-TSN/I-FORWARD-TSN chunks - when the sender
+  // wishes the received to skip/forget about data up until the provided TSN.
+  // This is used to implement partial reliability, such as limiting the number
+  // of retransmissions or the an expiration duration. As a result of skipping
+  // data, this may result in the implementation being able to assemble messages
+  // in ordered streams.
+  //
+  // Returns the number of bytes removed from the queue as a result of
+  // this operation.
+  virtual size_t HandleForwardTsn(
+      UnwrappedTSN new_cumulative_ack_tsn,
+      rtc::ArrayView<const AnyForwardTsnChunk::SkippedStream>
+          skipped_streams) = 0;
+
+  // Called for incoming (possibly deferred) RE_CONFIG chunks asking for
+  // either a few streams, or all streams (when the list is empty) to be
+  // reset - to have their next SSN or Message ID to be zero.
+  virtual void ResetStreams(rtc::ArrayView<const StreamID> stream_ids) = 0;
+
+  virtual HandoverReadinessStatus GetHandoverReadiness() const = 0;
+  virtual void AddHandoverState(DcSctpSocketHandoverState& state) = 0;
+  virtual void RestoreFromState(const DcSctpSocketHandoverState& state) = 0;
+};
+
+}  // namespace dcsctp
+
+#endif  // NET_DCSCTP_RX_REASSEMBLY_STREAMS_H_