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diff --git a/third_party/libwebrtc/net/dcsctp/socket/callback_deferrer.h b/third_party/libwebrtc/net/dcsctp/socket/callback_deferrer.h
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+++ b/third_party/libwebrtc/net/dcsctp/socket/callback_deferrer.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_SOCKET_CALLBACK_DEFERRER_H_
+#define NET_DCSCTP_SOCKET_CALLBACK_DEFERRER_H_
+
+#include <cstdint>
+#include <functional>
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "absl/strings/string_view.h"
+#include "api/array_view.h"
+#include "api/ref_counted_base.h"
+#include "api/scoped_refptr.h"
+#include "api/task_queue/task_queue_base.h"
+#include "net/dcsctp/public/dcsctp_message.h"
+#include "net/dcsctp/public/dcsctp_socket.h"
+
+namespace dcsctp {
+// Defers callbacks until they can be safely triggered.
+//
+// There are a lot of callbacks from the dcSCTP library to the client,
+// such as when messages are received or streams are closed. When the client
+// receives these callbacks, the client is expected to be able to call into the
+// library - from within the callback. For example, sending a reply message when
+// a certain SCTP message has been received, or to reconnect when the connection
+// was closed for any reason. This means that the dcSCTP library must always be
+// in a consistent and stable state when these callbacks are delivered, and to
+// ensure that's the case, callbacks are not immediately delivered from where
+// they originate, but instead queued (deferred) by this class. At the end of
+// any public API method that may result in callbacks, they are triggered and
+// then delivered.
+//
+// There are a number of exceptions, which is clearly annotated in the API.
+class CallbackDeferrer : public DcSctpSocketCallbacks {
+ public:
+  class ScopedDeferrer {
+   public:
+    explicit ScopedDeferrer(CallbackDeferrer& callback_deferrer)
+        : callback_deferrer_(callback_deferrer) {
+      callback_deferrer_.Prepare();
+    }
+
+    ~ScopedDeferrer() { callback_deferrer_.TriggerDeferred(); }
+
+   private:
+    CallbackDeferrer& callback_deferrer_;
+  };
+
+  explicit CallbackDeferrer(DcSctpSocketCallbacks& underlying)
+      : underlying_(underlying) {}
+
+  // Implementation of DcSctpSocketCallbacks
+  SendPacketStatus SendPacketWithStatus(
+      rtc::ArrayView<const uint8_t> data) override;
+  std::unique_ptr<Timeout> CreateTimeout(
+      webrtc::TaskQueueBase::DelayPrecision precision) override;
+  TimeMs TimeMillis() override;
+  uint32_t GetRandomInt(uint32_t low, uint32_t high) override;
+  void OnMessageReceived(DcSctpMessage message) override;
+  void OnError(ErrorKind error, absl::string_view message) override;
+  void OnAborted(ErrorKind error, absl::string_view message) override;
+  void OnConnected() override;
+  void OnClosed() override;
+  void OnConnectionRestarted() override;
+  void OnStreamsResetFailed(rtc::ArrayView<const StreamID> outgoing_streams,
+                            absl::string_view reason) override;
+  void OnStreamsResetPerformed(
+      rtc::ArrayView<const StreamID> outgoing_streams) override;
+  void OnIncomingStreamsReset(
+      rtc::ArrayView<const StreamID> incoming_streams) override;
+  void OnBufferedAmountLow(StreamID stream_id) override;
+  void OnTotalBufferedAmountLow() override;
+
+  void OnLifecycleMessageExpired(LifecycleId lifecycle_id,
+                                 bool maybe_delivered) override;
+  void OnLifecycleMessageFullySent(LifecycleId lifecycle_id) override;
+  void OnLifecycleMessageDelivered(LifecycleId lifecycle_id) override;
+  void OnLifecycleEnd(LifecycleId lifecycle_id) override;
+
+ private:
+  void Prepare();
+  void TriggerDeferred();
+
+  DcSctpSocketCallbacks& underlying_;
+  bool prepared_ = false;
+  std::vector<std::function<void(DcSctpSocketCallbacks& cb)>> deferred_;
+};
+}  // namespace dcsctp
+
+#endif  // NET_DCSCTP_SOCKET_CALLBACK_DEFERRER_H_