diff -r 000000000000 -r 6474c204b198 content/media/MediaMetadataManager.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/media/MediaMetadataManager.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,70 @@
+/* -*- 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 "VideoUtils.h"
+#include "mozilla/LinkedList.h"
+#include "AbstractMediaDecoder.h"
+#include "nsAutoPtr.h"
+
+namespace mozilla {
+
+  // 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:
+      // The time, in microseconds, at which those metadata should be available.
+      int64_t mPublishTime;
+      // The metadata. The ownership is transfered to the element when dispatching to
+      // the main threads.
+      nsAutoPtr<MetadataTags> mTags;
+      // The sample rate of this media.
+      int mRate;
+      // The number of channel of this media.
+      int mChannels;
+      // True if this media has an audio track.
+      bool mHasAudio;
+      // True if this media has a video track.
+      bool mHasVideo;
+  };
+
+  // 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;
+        }
+      }
+      void QueueMetadata(TimedMetadata* aMetadata) {
+        mMetadataQueue.insertBack(aMetadata);
+      }
+
+      void DispatchMetadataIfNeeded(AbstractMediaDecoder* aDecoder, double aCurrentTime) {
+        TimedMetadata* metadata = mMetadataQueue.getFirst();
+        while (metadata && aCurrentTime >= static_cast<double>(metadata->mPublishTime) / USECS_PER_S) {
+          nsCOMPtr<nsIRunnable> metadataUpdatedEvent =
+            new AudioMetadataEventRunner(aDecoder,
+                                         metadata->mChannels,
+                                         metadata->mRate,
+                                         metadata->mHasAudio,
+                                         metadata->mHasVideo,
+                                         metadata->mTags.forget());
+          NS_DispatchToMainThread(metadataUpdatedEvent, NS_DISPATCH_NORMAL);
+          delete mMetadataQueue.popFirst();
+          metadata = mMetadataQueue.getFirst();
+        }
+      }
+    protected:
+      LinkedList<TimedMetadata> mMetadataQueue;
+  };
+}
+
+#endif