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diff --git a/dom/media/mediacontrol/MediaController.h b/dom/media/mediacontrol/MediaController.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 DOM_MEDIA_MEDIACONTROL_MEDIACONTROLLER_H_
+#define DOM_MEDIA_MEDIACONTROL_MEDIACONTROLLER_H_
+
+#include "MediaEventSource.h"
+#include "MediaPlaybackStatus.h"
+#include "MediaStatusManager.h"
+#include "mozilla/DOMEventTargetHelper.h"
+#include "mozilla/dom/MediaControllerBinding.h"
+#include "mozilla/dom/MediaSession.h"
+#include "mozilla/LinkedList.h"
+#include "nsISupportsImpl.h"
+#include "nsITimer.h"
+
+namespace mozilla::dom {
+
+class BrowsingContext;
+
+/**
+ * IMediaController is an interface which includes control related methods and
+ * methods used to know its playback state.
+ */
+class IMediaController {
+ public:
+  NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
+
+  // Focus the window currently playing media.
+  virtual void Focus() = 0;
+  virtual void Play() = 0;
+  virtual void Pause() = 0;
+  virtual void Stop() = 0;
+  virtual void PrevTrack() = 0;
+  virtual void NextTrack() = 0;
+  virtual void SeekBackward() = 0;
+  virtual void SeekForward() = 0;
+  virtual void SkipAd() = 0;
+  virtual void SeekTo(double aSeekTime, bool aFastSeek) = 0;
+
+  // Return the ID of the top level browsing context within a tab.
+  virtual uint64_t Id() const = 0;
+  virtual bool IsAudible() const = 0;
+  virtual bool IsPlaying() const = 0;
+  virtual bool IsActive() const = 0;
+};
+
+/**
+ * MediaController is a class, which is used to control all media within a tab.
+ * It can only be used in Chrome process and the controlled media are usually
+ * in the content process (unless we disable e10s).
+ *
+ * Each tab would have only one media controller, they are 1-1 corresponding
+ * relationship, we use tab's top-level browsing context ID to initialize the
+ * controller and use that as its ID.
+ *
+ * The controller would be activated when its controlled media starts and
+ * becomes audible. After the controller is activated, then we can use its
+ * controlling methods, such as `Play()`, `Pause()` to control the media within
+ * the tab.
+ *
+ * If there is at least one controlled media playing in the tab, then we would
+ * say the controller is `playing`. If there is at least one controlled media is
+ * playing and audible, then we would say the controller is `audible`.
+ *
+ * Note that, if we don't enable audio competition, then we might have multiple
+ * tabs playing media at the same time, we can use the ID to query the specific
+ * controller from `MediaControlService`.
+ */
+class MediaController final : public DOMEventTargetHelper,
+                              public IMediaController,
+                              public LinkedListElement<RefPtr<MediaController>>,
+                              public MediaStatusManager,
+                              public nsITimerCallback,
+                              public nsINamed {
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSITIMERCALLBACK
+  NS_DECL_NSINAMED
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(MediaController,
+                                                         DOMEventTargetHelper)
+  explicit MediaController(uint64_t aBrowsingContextId);
+
+  // WebIDL methods
+  nsISupports* GetParentObject() const;
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+  void GetSupportedKeys(nsTArray<MediaControlKey>& aRetVal) const;
+  void GetMetadata(MediaMetadataInit& aMetadata, ErrorResult& aRv);
+  IMPL_EVENT_HANDLER(activated);
+  IMPL_EVENT_HANDLER(deactivated);
+  IMPL_EVENT_HANDLER(metadatachange);
+  IMPL_EVENT_HANDLER(supportedkeyschange);
+  IMPL_EVENT_HANDLER(playbackstatechange);
+  IMPL_EVENT_HANDLER(positionstatechange);
+
+  // IMediaController's methods
+  void Focus() override;
+  void Play() override;
+  void Pause() override;
+  void Stop() override;
+  void PrevTrack() override;
+  void NextTrack() override;
+  void SeekBackward() override;
+  void SeekForward() override;
+  void SkipAd() override;
+  void SeekTo(double aSeekTime, bool aFastSeek) override;
+
+  uint64_t Id() const override;
+  bool IsAudible() const override;
+  bool IsPlaying() const override;
+  bool IsActive() const override;
+
+  // IMediaInfoUpdater's methods
+  void NotifyMediaPlaybackChanged(uint64_t aBrowsingContextId,
+                                  MediaPlaybackState aState) override;
+  void NotifyMediaAudibleChanged(uint64_t aBrowsingContextId,
+                                 MediaAudibleState aState) override;
+  void SetIsInPictureInPictureMode(uint64_t aBrowsingContextId,
+                                   bool aIsInPictureInPictureMode) override;
+  void NotifyMediaFullScreenState(uint64_t aBrowsingContextId,
+                                  bool aIsInFullScreen) override;
+
+  // Calling this method explicitly would mark this controller as deprecated,
+  // then calling any its method won't take any effect.
+  void Shutdown();
+
+  // This event would be notified media controller's supported media keys
+  // change.
+  MediaEventSource<nsTArray<MediaControlKey>>& SupportedKeysChangedEvent() {
+    return mSupportedKeysChangedEvent;
+  }
+
+  MediaEventSource<bool>& FullScreenChangedEvent() {
+    return mFullScreenChangedEvent;
+  }
+
+  MediaEventSource<bool>& PictureInPictureModeChangedEvent() {
+    return mPictureInPictureModeChangedEvent;
+  }
+
+  CopyableTArray<MediaControlKey> GetSupportedMediaKeys() const;
+
+  bool IsBeingUsedInPIPModeOrFullscreen() const;
+
+  // These methods are used to select/unselect the media controller as a main
+  // controller.
+  void Select() const;
+  void Unselect() const;
+
+ private:
+  ~MediaController();
+  void HandleActualPlaybackStateChanged();
+  void UpdateMediaControlActionToContentMediaIfNeeded(
+      const MediaControlAction& aAction);
+  void HandleSupportedMediaSessionActionsChanged(
+      const nsTArray<MediaSessionAction>& aSupportedAction);
+
+  void HandlePositionStateChanged(const PositionState& aState);
+  void HandleMetadataChanged(const MediaMetadataBase& aMetadata);
+
+  // This would register controller to the media control service that takes a
+  // responsibility to manage all active controllers.
+  void Activate();
+
+  // This would unregister controller from the media control service.
+  void Deactivate();
+
+  void UpdateActivatedStateIfNeeded();
+  bool ShouldActivateController() const;
+  bool ShouldDeactivateController() const;
+
+  void UpdateDeactivationTimerIfNeeded();
+
+  void DispatchAsyncEvent(const nsAString& aName);
+  void DispatchAsyncEvent(Event* aEvent);
+
+  bool IsMainController() const;
+  void ForceToBecomeMainControllerIfNeeded();
+  bool ShouldRequestForMainController() const;
+
+  bool ShouldPropagateActionToAllContexts(
+      const MediaControlAction& aAction) const;
+
+  bool mIsActive = false;
+  bool mShutdown = false;
+  bool mIsInPictureInPictureMode = false;
+  bool mIsInFullScreenMode = false;
+
+  // We would monitor the change of media session actions and convert them to
+  // the media keys, then determine the supported media keys.
+  MediaEventListener mSupportedActionsChangedListener;
+  MediaEventProducer<nsTArray<MediaControlKey>> mSupportedKeysChangedEvent;
+
+  MediaEventListener mPlaybackChangedListener;
+  MediaEventListener mPositionStateChangedListener;
+  MediaEventListener mMetadataChangedListener;
+
+  MediaEventProducer<bool> mFullScreenChangedEvent;
+  MediaEventProducer<bool> mPictureInPictureModeChangedEvent;
+  // Use copyable array so that we can use the result as a parameter for the
+  // media event.
+  CopyableTArray<MediaControlKey> mSupportedKeys;
+  // Timer to deactivate the controller if the time of being paused exceeds the
+  // threshold of time.
+  nsCOMPtr<nsITimer> mDeactivationTimer;
+};
+
+}  // namespace mozilla::dom
+
+#endif