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diff --git a/third_party/libwebrtc/webrtc/video/stream_synchronization.h b/third_party/libwebrtc/webrtc/video/stream_synchronization.h
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+++ b/third_party/libwebrtc/webrtc/video/stream_synchronization.h
@@ -0,0 +1,63 @@
+/*
+ *  Copyright (c) 2012 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 VIDEO_STREAM_SYNCHRONIZATION_H_
+#define VIDEO_STREAM_SYNCHRONIZATION_H_
+
+#include <list>
+
+#include "system_wrappers/include/rtp_to_ntp_estimator.h"
+#include "typedefs.h"  // NOLINT(build/include)
+
+namespace webrtc {
+
+class StreamSynchronization {
+ public:
+  struct Measurements {
+    Measurements() : latest_receive_time_ms(0), latest_timestamp(0) {}
+    RtpToNtpEstimator rtp_to_ntp;
+    int64_t latest_receive_time_ms;
+    uint32_t latest_timestamp;
+  };
+
+  StreamSynchronization(int video_stream_id, int audio_stream_id);
+
+  bool ComputeDelays(int relative_delay_ms,
+                     int current_audio_delay_ms,
+                     int* extra_audio_delay_ms,
+                     int* total_video_delay_target_ms);
+
+  // On success |relative_delay| contains the number of milliseconds later video
+  // is rendered relative audio. If audio is played back later than video a
+  // |relative_delay| will be negative.
+  static bool ComputeRelativeDelay(const Measurements& audio_measurement,
+                                   const Measurements& video_measurement,
+                                   int* relative_delay_ms);
+  // Set target buffering delay - All audio and video will be delayed by at
+  // least target_delay_ms.
+  void SetTargetBufferingDelay(int target_delay_ms);
+
+ private:
+  struct SynchronizationDelays {
+    int extra_video_delay_ms = 0;
+    int last_video_delay_ms = 0;
+    int extra_audio_delay_ms = 0;
+    int last_audio_delay_ms = 0;
+  };
+
+  SynchronizationDelays channel_delay_;
+  const int video_stream_id_;
+  const int audio_stream_id_;
+  int base_target_delay_ms_;
+  int avg_diff_ms_;
+};
+}  // namespace webrtc
+
+#endif  // VIDEO_STREAM_SYNCHRONIZATION_H_