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diff --git a/dom/media/CrossGraphPort.h b/dom/media/CrossGraphPort.h
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+++ b/dom/media/CrossGraphPort.h
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_CROSS_GRAPH_TRACK_H_
+#define MOZILLA_CROSS_GRAPH_TRACK_H_
+
+#include "AudioDriftCorrection.h"
+#include "AudioSegment.h"
+#include "ForwardedInputTrack.h"
+#include "mozilla/SPSCQueue.h"
+#include "mozilla/UniquePtr.h"
+
+namespace mozilla {
+class CrossGraphReceiver;
+}
+
+namespace mozilla::dom {
+class AudioStreamTrack;
+}
+
+namespace mozilla {
+
+/**
+ * CrossGraphTransmitter and CrossGraphPort are currently unused, but intended
+ * for connecting MediaTracks of different MediaTrackGraphs with different
+ * sample rates or clock sources for bug 1674892.
+ *
+ * Create with MediaTrackGraph::CreateCrossGraphTransmitter()
+ */
+class CrossGraphTransmitter : public ProcessedMediaTrack {
+ public:
+  CrossGraphTransmitter(TrackRate aSampleRate,
+                        RefPtr<CrossGraphReceiver> aReceiver);
+  CrossGraphTransmitter* AsCrossGraphTransmitter() override { return this; }
+
+  uint32_t NumberOfChannels() const override {
+    MOZ_CRASH("CrossGraphTransmitter has no segment. It cannot be played out.");
+  }
+  void ProcessInput(GraphTime aFrom, GraphTime aTo, uint32_t aFlags) override;
+
+ private:
+  const RefPtr<CrossGraphReceiver> mReceiver;
+};
+
+/**
+ * Create with MediaTrackGraph::CreateCrossGraphReceiver()
+ */
+class CrossGraphReceiver : public ProcessedMediaTrack {
+ public:
+  CrossGraphReceiver(TrackRate aSampleRate, TrackRate aTransmitterRate);
+  CrossGraphReceiver* AsCrossGraphReceiver() override { return this; }
+
+  uint32_t NumberOfChannels() const override;
+  void ProcessInput(GraphTime aFrom, GraphTime aTo, uint32_t aFlags) override;
+
+  int EnqueueAudio(AudioChunk& aChunk);
+
+ private:
+  SPSCQueue<AudioChunk> mCrossThreadFIFO{30};
+  // Indicates that tre CrossGraphTransmitter has started sending frames. It
+  // is false untill the point, transmitter has sent the first valid frame.
+  // Accessed in GraphThread only.
+  bool mTransmitterHasStarted = false;
+  // Correct the drift between transmitter and receiver. Reciever (this class)
+  // is considered as the master clock.
+  // Accessed in GraphThread only.
+  AudioDriftCorrection mDriftCorrection;
+};
+
+class CrossGraphPort final {
+ public:
+  static UniquePtr<CrossGraphPort> Connect(
+      const RefPtr<dom::AudioStreamTrack>& aStreamTrack,
+      MediaTrackGraph* aPartnerGraph);
+  ~CrossGraphPort();
+
+  const RefPtr<CrossGraphTransmitter> mTransmitter;
+  const RefPtr<CrossGraphReceiver> mReceiver;
+
+ private:
+  explicit CrossGraphPort(RefPtr<MediaInputPort> aTransmitterPort,
+                          RefPtr<CrossGraphTransmitter> aTransmitter,
+                          RefPtr<CrossGraphReceiver> aReceiver)
+      : mTransmitter(std::move(aTransmitter)),
+        mReceiver(std::move(aReceiver)),
+        mTransmitterPort(std::move(aTransmitterPort)) {
+    MOZ_ASSERT(mTransmitter);
+    MOZ_ASSERT(mReceiver);
+    MOZ_ASSERT(mTransmitterPort);
+  }
+
+  // The port that connects the input track to the transmitter.
+  const RefPtr<MediaInputPort> mTransmitterPort;
+};
+
+}  // namespace mozilla
+
+#endif /* MOZILLA_CROSS_GRAPH_TRACK_H_ */