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diff --git a/third_party/libwebrtc/logging/rtc_event_log/rtc_event_processor.h b/third_party/libwebrtc/logging/rtc_event_log/rtc_event_processor.h
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+++ b/third_party/libwebrtc/logging/rtc_event_log/rtc_event_processor.h
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+/*
+ *  Copyright (c) 2018 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 LOGGING_RTC_EVENT_LOG_RTC_EVENT_PROCESSOR_H_
+#define LOGGING_RTC_EVENT_LOG_RTC_EVENT_PROCESSOR_H_
+
+#include <stdint.h>
+
+#include <algorithm>
+#include <memory>
+#include <utility>
+#include <vector>
+
+#include "api/function_view.h"
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+
+// This file contains helper class used to process the elements of two or more
+// sorted lists in timestamp order. The effect is the same as doing a merge step
+// in the merge-sort algorithm but without copying the elements or modifying the
+// lists.
+
+namespace event_processor_impl {
+// Interface to allow "merging" lists of different types. ProcessNext()
+// processes the next unprocesses element in the list. IsEmpty() checks if all
+// elements have been processed. GetNextTime returns the timestamp of the next
+// unprocessed element.
+class ProcessableEventListInterface {
+ public:
+  virtual ~ProcessableEventListInterface() = default;
+  virtual void ProcessNext() = 0;
+  virtual bool IsEmpty() const = 0;
+  virtual int64_t GetNextTime() const = 0;
+  virtual int GetTieBreaker() const = 0;
+};
+
+// ProcessableEventList encapsulates a list of events and a function that will
+// be applied to each element of the list.
+template <typename Iterator, typename T>
+class ProcessableEventList : public ProcessableEventListInterface {
+ public:
+  ProcessableEventList(Iterator begin,
+                       Iterator end,
+                       std::function<void(const T&)> f,
+                       int tie_breaker)
+      : begin_(begin), end_(end), f_(f), tie_breaker_(tie_breaker) {}
+
+  void ProcessNext() override {
+    RTC_DCHECK(!IsEmpty());
+    f_(*begin_);
+    ++begin_;
+  }
+
+  bool IsEmpty() const override { return begin_ == end_; }
+
+  int64_t GetNextTime() const override {
+    RTC_DCHECK(!IsEmpty());
+    return begin_->log_time_us();
+  }
+  int GetTieBreaker() const override { return tie_breaker_; }
+
+ private:
+  Iterator begin_;
+  Iterator end_;
+  std::function<void(const T&)> f_;
+  int tie_breaker_;
+};
+}  // namespace event_processor_impl
+
+// Helper class used to "merge" two or more lists of ordered RtcEventLog events
+// so that they can be treated as a single ordered list. Since the individual
+// lists may have different types, we need to access the lists via pointers to
+// the common base class.
+//
+// Usage example:
+// ParsedRtcEventLogNew log;
+// auto incoming_handler = [] (LoggedRtcpPacketIncoming elem) { ... };
+// auto outgoing_handler = [] (LoggedRtcpPacketOutgoing elem) { ... };
+//
+// RtcEventProcessor processor;
+// processor.AddEvents(log.incoming_rtcp_packets(),
+//                     incoming_handler);
+// processor.AddEvents(log.outgoing_rtcp_packets(),
+//                     outgoing_handler);
+// processor.ProcessEventsInOrder();
+class RtcEventProcessor {
+ public:
+  RtcEventProcessor();
+  ~RtcEventProcessor();
+  // The elements of each list is processed in the index order. To process all
+  // elements in all lists in timestamp order, each list needs to be sorted in
+  // timestamp order prior to insertion.
+  // N.B. `iterable` is not owned by RtcEventProcessor. The caller must ensure
+  // that the iterable outlives RtcEventProcessor and it must not be modified
+  // until processing has finished.
+  template <typename Iterable>
+  void AddEvents(
+      const Iterable& iterable,
+      std::function<void(const typename Iterable::value_type&)> handler) {
+    if (iterable.begin() == iterable.end())
+      return;
+    event_lists_.push_back(
+        std::make_unique<event_processor_impl::ProcessableEventList<
+            typename Iterable::const_iterator, typename Iterable::value_type>>(
+            iterable.begin(), iterable.end(), handler,
+            insertion_order_index_++));
+    std::push_heap(event_lists_.begin(), event_lists_.end(), Cmp);
+  }
+
+  void ProcessEventsInOrder();
+
+ private:
+  using ListPtrType =
+      std::unique_ptr<event_processor_impl::ProcessableEventListInterface>;
+  int insertion_order_index_ = 0;
+  std::vector<ListPtrType> event_lists_;
+  // Comparison function to make `event_lists_` into a min heap.
+  static bool Cmp(const ListPtrType& a, const ListPtrType& b);
+};
+
+}  // namespace webrtc
+
+#endif  // LOGGING_RTC_EVENT_LOG_RTC_EVENT_PROCESSOR_H_