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diff --git a/dom/media/MediaMetadataManager.h b/dom/media/MediaMetadataManager.h
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+++ b/dom/media/MediaMetadataManager.h
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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/. */
+
+#if !defined(MediaMetadataManager_h__)
+#  define MediaMetadataManager_h__
+
+#  include "mozilla/AbstractThread.h"
+#  include "mozilla/LinkedList.h"
+
+#  include "MediaEventSource.h"
+#  include "TimeUnits.h"
+#  include "VideoUtils.h"
+
+namespace mozilla {
+
+class TimedMetadata;
+typedef MediaEventProducerExc<TimedMetadata> TimedMetadataEventProducer;
+typedef MediaEventSourceExc<TimedMetadata> TimedMetadataEventSource;
+
+// A struct that contains the metadata of a media, and the time at which those
+// metadata should start to be reported.
+class TimedMetadata : public LinkedListElement<TimedMetadata> {
+ public:
+  TimedMetadata(const media::TimeUnit& aPublishTime,
+                UniquePtr<MetadataTags>&& aTags, UniquePtr<MediaInfo>&& aInfo)
+      : mPublishTime(aPublishTime),
+        mTags(std::move(aTags)),
+        mInfo(std::move(aInfo)) {}
+
+  // Define our move constructor because we don't want to move the members of
+  // LinkedListElement to change the list.
+  TimedMetadata(TimedMetadata&& aOther)
+      : mPublishTime(aOther.mPublishTime),
+        mTags(std::move(aOther.mTags)),
+        mInfo(std::move(aOther.mInfo)) {}
+
+  // The time, in microseconds, at which those metadata should be available.
+  media::TimeUnit mPublishTime;
+  // The metadata. The ownership is transfered to the element when dispatching
+  // to the main threads.
+  UniquePtr<MetadataTags> mTags;
+  // The media info, including the info of audio tracks and video tracks.
+  // The ownership is transfered to MediaDecoder when dispatching to the
+  // main thread.
+  UniquePtr<MediaInfo> mInfo;
+};
+
+// This class encapsulate the logic to give the metadata from the reader to
+// the content, at the right time.
+class MediaMetadataManager {
+ public:
+  ~MediaMetadataManager() {
+    TimedMetadata* element;
+    while ((element = mMetadataQueue.popFirst()) != nullptr) {
+      delete element;
+    }
+  }
+
+  // Connect to an event source to receive TimedMetadata events.
+  void Connect(TimedMetadataEventSource& aEvent, AbstractThread* aThread) {
+    mListener =
+        aEvent.Connect(aThread, this, &MediaMetadataManager::OnMetadataQueued);
+  }
+
+  // Stop receiving TimedMetadata events.
+  void Disconnect() { mListener.Disconnect(); }
+
+  // Return an event source through which we will send TimedMetadata events
+  // when playback position reaches the publish time.
+  TimedMetadataEventSource& TimedMetadataEvent() { return mTimedMetadataEvent; }
+
+  void DispatchMetadataIfNeeded(const media::TimeUnit& aCurrentTime) {
+    TimedMetadata* metadata = mMetadataQueue.getFirst();
+    while (metadata && aCurrentTime >= metadata->mPublishTime) {
+      // Our listener will figure out what to do with TimedMetadata.
+      mTimedMetadataEvent.Notify(std::move(*metadata));
+      delete mMetadataQueue.popFirst();
+      metadata = mMetadataQueue.getFirst();
+    }
+  }
+
+ protected:
+  void OnMetadataQueued(TimedMetadata&& aMetadata) {
+    mMetadataQueue.insertBack(new TimedMetadata(std::move(aMetadata)));
+  }
+
+  LinkedList<TimedMetadata> mMetadataQueue;
+  MediaEventListener mListener;
+  TimedMetadataEventProducer mTimedMetadataEvent;
+};
+
+}  // namespace mozilla
+
+#endif