Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1941 insertions, 0 deletions

diff --git a/dom/html/HTMLMediaElement.h b/dom/html/HTMLMediaElement.h
new file mode 100644
index 0000000000..0d35fcc85c
--- /dev/null
+++ b/dom/html/HTMLMediaElement.h
@@ -0,0 +1,1941 @@
+/* -*- 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 mozilla_dom_HTMLMediaElement_h
+#define mozilla_dom_HTMLMediaElement_h
+
+#include "nsGenericHTMLElement.h"
+#include "AudioChannelService.h"
+#include "MediaEventSource.h"
+#include "SeekTarget.h"
+#include "MediaDecoderOwner.h"
+#include "MediaElementEventRunners.h"
+#include "MediaPlaybackDelayPolicy.h"
+#include "MediaPromiseDefs.h"
+#include "TelemetryProbesReporter.h"
+#include "nsCycleCollectionParticipant.h"
+#include "Visibility.h"
+#include "mozilla/CORSMode.h"
+#include "DecoderTraits.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/StateWatching.h"
+#include "mozilla/WeakPtr.h"
+#include "mozilla/dom/DecoderDoctorNotificationBinding.h"
+#include "mozilla/dom/HTMLMediaElementBinding.h"
+#include "mozilla/dom/MediaDebugInfoBinding.h"
+#include "mozilla/dom/MediaKeys.h"
+#include "mozilla/dom/TextTrackManager.h"
+#include "nsGkAtoms.h"
+#include "PrincipalChangeObserver.h"
+#include "nsStubMutationObserver.h"
+#include "MediaSegment.h"  // for PrincipalHandle, GraphTime
+
+#include <utility>
+
+// X.h on Linux #defines CurrentTime as 0L, so we have to #undef it here.
+#ifdef CurrentTime
+#  undef CurrentTime
+#endif
+
+// Define to output information on decoding and painting framerate
+/* #define DEBUG_FRAME_RATE 1 */
+
+using nsMediaNetworkState = uint16_t;
+using nsMediaReadyState = uint16_t;
+using SuspendTypes = uint32_t;
+using AudibleChangedReasons = uint32_t;
+
+class nsIStreamListener;
+
+namespace mozilla {
+class AbstractThread;
+class ChannelMediaDecoder;
+class DecoderDoctorDiagnostics;
+class DOMMediaStream;
+class ErrorResult;
+class FirstFrameVideoOutput;
+class MediaResource;
+class MediaDecoder;
+class MediaInputPort;
+class MediaTrack;
+class MediaTrackGraph;
+class MediaStreamWindowCapturer;
+struct SharedDummyTrack;
+class VideoFrameContainer;
+class VideoOutput;
+namespace dom {
+class HTMLSourceElement;
+class MediaKeys;
+class TextTrack;
+class TimeRanges;
+class WakeLock;
+class MediaStreamTrack;
+class MediaStreamTrackSource;
+class MediaTrack;
+class VideoStreamTrack;
+}  // namespace dom
+}  // namespace mozilla
+
+class AudioDeviceInfo;
+class nsIChannel;
+class nsIHttpChannel;
+class nsILoadGroup;
+class nsIRunnable;
+class nsISerialEventTarget;
+class nsITimer;
+class nsRange;
+
+namespace mozilla::dom {
+
+// Number of milliseconds between timeupdate events as defined by spec
+#define TIMEUPDATE_MS 250
+
+class MediaError;
+class MediaSource;
+class PlayPromise;
+class Promise;
+class TextTrackList;
+class AudioTrackList;
+class VideoTrackList;
+
+enum class StreamCaptureType : uint8_t { CAPTURE_ALL_TRACKS, CAPTURE_AUDIO };
+
+enum class StreamCaptureBehavior : uint8_t {
+  CONTINUE_WHEN_ENDED,
+  FINISH_WHEN_ENDED
+};
+
+class HTMLMediaElement : public nsGenericHTMLElement,
+                         public MediaDecoderOwner,
+                         public PrincipalChangeObserver<MediaStreamTrack>,
+                         public SupportsWeakPtr,
+                         public nsStubMutationObserver,
+                         public TelemetryProbesReporterOwner {
+ public:
+  using TimeStamp = mozilla::TimeStamp;
+  using ImageContainer = mozilla::layers::ImageContainer;
+  using VideoFrameContainer = mozilla::VideoFrameContainer;
+  using MediaResource = mozilla::MediaResource;
+  using MediaDecoderOwner = mozilla::MediaDecoderOwner;
+  using MetadataTags = mozilla::MetadataTags;
+
+  // Helper struct to keep track of the MediaStreams returned by
+  // mozCaptureStream(). For each OutputMediaStream, dom::MediaTracks get
+  // captured into MediaStreamTracks which get added to
+  // OutputMediaStream::mStream.
+  struct OutputMediaStream {
+    OutputMediaStream(RefPtr<DOMMediaStream> aStream, bool aCapturingAudioOnly,
+                      bool aFinishWhenEnded);
+    ~OutputMediaStream();
+
+    RefPtr<DOMMediaStream> mStream;
+    nsTArray<RefPtr<MediaStreamTrack>> mLiveTracks;
+    const bool mCapturingAudioOnly;
+    const bool mFinishWhenEnded;
+    // If mFinishWhenEnded is true, this is the URI of the first resource
+    // mStream got tracks for.
+    nsCOMPtr<nsIURI> mFinishWhenEndedLoadingSrc;
+    // If mFinishWhenEnded is true, this is the first MediaStream mStream got
+    // tracks for.
+    RefPtr<DOMMediaStream> mFinishWhenEndedAttrStream;
+    // If mFinishWhenEnded is true, this is the MediaSource being played.
+    RefPtr<MediaSource> mFinishWhenEndedMediaSource;
+  };
+
+  NS_DECL_NSIMUTATIONOBSERVER_CONTENTREMOVED
+
+  CORSMode GetCORSMode() { return mCORSMode; }
+
+  explicit HTMLMediaElement(
+      already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo);
+  void Init();
+
+  // `eMandatory`: `timeupdate` occurs according to the spec requirement.
+  // Eg.
+  // https://html.spec.whatwg.org/multipage/media.html#seeking:event-media-timeupdate
+  // `ePeriodic` : `timeupdate` occurs regularly and should follow the rule
+  // of not dispatching that event within 250 ms. Eg.
+  // https://html.spec.whatwg.org/multipage/media.html#offsets-into-the-media-resource:event-media-timeupdate
+  enum class TimeupdateType : bool {
+    eMandatory = false,
+    ePeriodic = true,
+  };
+
+  // This is used for event runner creation. Currently only timeupdate needs
+  // that, but it can be used to extend for other events in the future if
+  // necessary.
+  enum class EventFlag : uint8_t {
+    eNone = 0,
+    eMandatory = 1,
+  };
+
+  /**
+   * This is used when the browser is constructing a video element to play
+   * a channel that we've already started loading. The src attribute and
+   * <source> children are ignored.
+   * @param aChannel the channel to use
+   * @param aListener returns a stream listener that should receive
+   * notifications for the stream
+   */
+  nsresult LoadWithChannel(nsIChannel* aChannel, nsIStreamListener** aListener);
+
+  // nsISupports
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(HTMLMediaElement,
+                                           nsGenericHTMLElement)
+  NS_IMPL_FROMNODE_HELPER(HTMLMediaElement,
+                          IsAnyOfHTMLElements(nsGkAtoms::video,
+                                              nsGkAtoms::audio))
+
+  NS_DECL_ADDSIZEOFEXCLUDINGTHIS
+
+  // EventTarget
+  void GetEventTargetParent(EventChainPreVisitor& aVisitor) override;
+
+  void NodeInfoChanged(Document* aOldDoc) override;
+
+  virtual bool ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
+                              const nsAString& aValue,
+                              nsIPrincipal* aMaybeScriptedPrincipal,
+                              nsAttrValue& aResult) override;
+
+  virtual nsresult BindToTree(BindContext&, nsINode& aParent) override;
+  virtual void UnbindFromTree(bool aNullParent = true) override;
+  virtual void DoneCreatingElement() override;
+
+  virtual bool IsHTMLFocusable(bool aWithMouse, bool* aIsFocusable,
+                               int32_t* aTabIndex) override;
+  virtual int32_t TabIndexDefault() override;
+
+  // Called by the video decoder object, on the main thread,
+  // when it has read the metadata containing video dimensions,
+  // etc.
+  virtual void MetadataLoaded(const MediaInfo* aInfo,
+                              UniquePtr<const MetadataTags> aTags) final;
+
+  // Called by the decoder object, on the main thread,
+  // when it has read the first frame of the video or audio.
+  void FirstFrameLoaded() final;
+
+  // Called by the video decoder object, on the main thread,
+  // when the resource has a network error during loading.
+  void NetworkError(const MediaResult& aError) final;
+
+  // Called by the video decoder object, on the main thread, when the
+  // resource has a decode error during metadata loading or decoding.
+  void DecodeError(const MediaResult& aError) final;
+
+  // Called by the decoder object, on the main thread, when the
+  // resource has a decode issue during metadata loading or decoding, but can
+  // continue decoding.
+  void DecodeWarning(const MediaResult& aError) final;
+
+  // Return true if error attribute is not null.
+  bool HasError() const final;
+
+  // Called by the video decoder object, on the main thread, when the
+  // resource load has been cancelled.
+  void LoadAborted() final;
+
+  // Called by the video decoder object, on the main thread,
+  // when the video playback has ended.
+  void PlaybackEnded() final;
+
+  // Called by the video decoder object, on the main thread,
+  // when the resource has started seeking.
+  void SeekStarted() final;
+
+  // Called by the video decoder object, on the main thread,
+  // when the resource has completed seeking.
+  void SeekCompleted() final;
+
+  // Called by the video decoder object, on the main thread,
+  // when the resource has aborted seeking.
+  void SeekAborted() final;
+
+  // Called by the media stream, on the main thread, when the download
+  // has been suspended by the cache or because the element itself
+  // asked the decoder to suspend the download.
+  void DownloadSuspended() final;
+
+  // Called by the media stream, on the main thread, when the download
+  // has been resumed by the cache or because the element itself
+  // asked the decoder to resumed the download.
+  void DownloadResumed();
+
+  // Called to indicate the download is progressing.
+  void DownloadProgressed() final;
+
+  // Called by the media decoder to indicate whether the media cache has
+  // suspended the channel.
+  void NotifySuspendedByCache(bool aSuspendedByCache) final;
+
+  // Return true if the media element is actually invisible to users.
+  bool IsActuallyInvisible() const override;
+
+  // Return true if the element is in the view port.
+  bool IsInViewPort() const;
+
+  // Called by the media decoder and the video frame to get the
+  // ImageContainer containing the video data.
+  VideoFrameContainer* GetVideoFrameContainer() final;
+  layers::ImageContainer* GetImageContainer();
+
+  /**
+   * Call this to reevaluate whether we should start/stop due to our owner
+   * document being active, inactive, visible or hidden.
+   */
+  void NotifyOwnerDocumentActivityChanged();
+
+  // Called when the media element enters or leaves the fullscreen.
+  void NotifyFullScreenChanged();
+
+  bool IsInFullScreen() const;
+
+  // From PrincipalChangeObserver<MediaStreamTrack>.
+  void PrincipalChanged(MediaStreamTrack* aTrack) override;
+
+  void UpdateSrcStreamVideoPrincipal(const PrincipalHandle& aPrincipalHandle);
+
+  // Called after the MediaStream we're playing rendered a frame to aContainer
+  // with a different principalHandle than the previous frame.
+  void PrincipalHandleChangedForVideoFrameContainer(
+      VideoFrameContainer* aContainer,
+      const PrincipalHandle& aNewPrincipalHandle) override;
+
+  // Dispatch events
+  void DispatchAsyncEvent(const nsAString& aName) final;
+  void DispatchAsyncEvent(RefPtr<nsMediaEventRunner> aRunner);
+
+  // Triggers a recomputation of readyState.
+  void UpdateReadyState() override {
+    mWatchManager.ManualNotify(&HTMLMediaElement::UpdateReadyStateInternal);
+  }
+
+  // Dispatch events that were raised while in the bfcache
+  nsresult DispatchPendingMediaEvents();
+
+  // Return true if we can activate autoplay assuming enough data has arrived.
+  // https://html.spec.whatwg.org/multipage/media.html#eligible-for-autoplay
+  bool IsEligibleForAutoplay();
+
+  // Notify that state has changed that might cause an autoplay element to
+  // start playing.
+  // If the element is 'autoplay' and is ready to play back (not paused,
+  // autoplay pref enabled, etc), it should start playing back.
+  void CheckAutoplayDataReady();
+
+  void RunAutoplay();
+
+  // Check if the media element had crossorigin set when loading started
+  bool ShouldCheckAllowOrigin();
+
+  // Returns true if the currently loaded resource is CORS same-origin with
+  // respect to the document.
+  bool IsCORSSameOrigin();
+
+  // Is the media element potentially playing as defined by the HTML 5
+  // specification.
+  // http://www.whatwg.org/specs/web-apps/current-work/#potentially-playing
+  bool IsPotentiallyPlaying() const;
+
+  // Has playback ended as defined by the HTML 5 specification.
+  // http://www.whatwg.org/specs/web-apps/current-work/#ended
+  bool IsPlaybackEnded() const;
+
+  // principal of the currently playing resource. Anything accessing the
+  // contents of this element must have a principal that subsumes this
+  // principal. Returns null if nothing is playing.
+  already_AddRefed<nsIPrincipal> GetCurrentPrincipal();
+
+  // Return true if the loading of this resource required cross-origin
+  // redirects.
+  bool HadCrossOriginRedirects();
+
+  bool ShouldResistFingerprinting(RFPTarget aTarget) const override;
+
+  // Principal of the currently playing video resource. Anything accessing the
+  // image container of this element must have a principal that subsumes this
+  // principal. If there are no live video tracks but content has been rendered
+  // to the image container, we return the last video principal we had. Should
+  // the image container be empty with no live video tracks, we return nullptr.
+  already_AddRefed<nsIPrincipal> GetCurrentVideoPrincipal();
+
+  // called to notify that the principal of the decoder's media resource has
+  // changed.
+  void NotifyDecoderPrincipalChanged() final;
+
+  void GetEMEInfo(dom::EMEDebugInfo& aInfo);
+
+  // Update the visual size of the media. Called from the decoder on the
+  // main thread when/if the size changes.
+  virtual void UpdateMediaSize(const nsIntSize& aSize);
+
+  void Invalidate(ImageSizeChanged aImageSizeChanged,
+                  const Maybe<nsIntSize>& aNewIntrinsicSize,
+                  ForceInvalidate aForceInvalidate) override;
+
+  // Returns the CanPlayStatus indicating if we can handle the
+  // full MIME type including the optional codecs parameter.
+  static CanPlayStatus GetCanPlay(const nsAString& aType,
+                                  DecoderDoctorDiagnostics* aDiagnostics);
+
+  /**
+   * Called when a child source element is added to this media element. This
+   * may queue a task to run the select resource algorithm if appropriate.
+   */
+  void NotifyAddedSource();
+
+  /**
+   * Called when there's been an error fetching the resource. This decides
+   * whether it's appropriate to fire an error event.
+   */
+  void NotifyLoadError(const nsACString& aErrorDetails = nsCString());
+
+  /**
+   * Called by one of our associated MediaTrackLists (audio/video) when a
+   * MediaTrack is added.
+   */
+  void NotifyMediaTrackAdded(dom::MediaTrack* aTrack);
+
+  /**
+   * Called by one of our associated MediaTrackLists (audio/video) when a
+   * MediaTrack is removed.
+   */
+  void NotifyMediaTrackRemoved(dom::MediaTrack* aTrack);
+
+  /**
+   * Called by one of our associated MediaTrackLists (audio/video) when an
+   * AudioTrack is enabled or a VideoTrack is selected.
+   */
+  void NotifyMediaTrackEnabled(dom::MediaTrack* aTrack);
+
+  /**
+   * Called by one of our associated MediaTrackLists (audio/video) when an
+   * AudioTrack is disabled or a VideoTrack is unselected.
+   */
+  void NotifyMediaTrackDisabled(dom::MediaTrack* aTrack);
+
+  /**
+   * Returns the current load ID. Asynchronous events store the ID that was
+   * current when they were enqueued, and if it has changed when they come to
+   * fire, they consider themselves cancelled, and don't fire.
+   */
+  uint32_t GetCurrentLoadID() const { return mCurrentLoadID; }
+
+  /**
+   * Returns the load group for this media element's owner document.
+   * XXX XBL2 issue.
+   */
+  already_AddRefed<nsILoadGroup> GetDocumentLoadGroup();
+
+  /**
+   * Returns true if the media has played or completed a seek.
+   * Used by video frame to determine whether to paint the poster.
+   */
+  bool GetPlayedOrSeeked() const { return mHasPlayedOrSeeked; }
+
+  nsresult CopyInnerTo(Element* aDest);
+
+  /**
+   * Sets the Accept header on the HTTP channel to the required
+   * video or audio MIME types.
+   */
+  virtual nsresult SetAcceptHeader(nsIHttpChannel* aChannel) = 0;
+
+  /**
+   * Sets the required request headers on the HTTP channel for
+   * video or audio requests.
+   */
+  void SetRequestHeaders(nsIHttpChannel* aChannel);
+
+  /**
+   * Asynchronously awaits a stable state, whereupon aRunnable runs on the main
+   * thread. This adds an event which run aRunnable to the appshell's list of
+   * sections synchronous the next time control returns to the event loop.
+   */
+  void RunInStableState(nsIRunnable* aRunnable);
+
+  /**
+   * Fires a timeupdate event. If aPeriodic is true, the event will only
+   * be fired if we've not fired a timeupdate event (for any reason) in the
+   * last 250ms, as required by the spec when the current time is periodically
+   * increasing during playback.
+   */
+  void FireTimeUpdate(TimeupdateType aType);
+
+  void MaybeQueueTimeupdateEvent() final {
+    FireTimeUpdate(TimeupdateType::ePeriodic);
+  }
+
+  const TimeStamp& LastTimeupdateDispatchTime() const;
+  void UpdateLastTimeupdateDispatchTime();
+
+  // WebIDL
+
+  MediaError* GetError() const;
+
+  void GetSrc(nsAString& aSrc) { GetURIAttr(nsGkAtoms::src, nullptr, aSrc); }
+  void SetSrc(const nsAString& aSrc, ErrorResult& aError) {
+    SetHTMLAttr(nsGkAtoms::src, aSrc, aError);
+  }
+  void SetSrc(const nsAString& aSrc, nsIPrincipal* aTriggeringPrincipal,
+              ErrorResult& aError) {
+    SetHTMLAttr(nsGkAtoms::src, aSrc, aTriggeringPrincipal, aError);
+  }
+
+  void GetCurrentSrc(nsAString& aCurrentSrc);
+
+  void GetCrossOrigin(nsAString& aResult) {
+    // Null for both missing and invalid defaults is ok, since we
+    // always parse to an enum value, so we don't need an invalid
+    // default, and we _want_ the missing default to be null.
+    GetEnumAttr(nsGkAtoms::crossorigin, nullptr, aResult);
+  }
+  void SetCrossOrigin(const nsAString& aCrossOrigin, ErrorResult& aError) {
+    SetOrRemoveNullableStringAttr(nsGkAtoms::crossorigin, aCrossOrigin, aError);
+  }
+
+  uint16_t NetworkState() const { return mNetworkState; }
+
+  void NotifyXPCOMShutdown() final;
+
+  // Called by media decoder when the audible state changed or when input is
+  // a media stream.
+  void SetAudibleState(bool aAudible) final;
+
+  // Notify agent when the MediaElement changes its audible state.
+  void NotifyAudioPlaybackChanged(AudibleChangedReasons aReason);
+
+  void GetPreload(nsAString& aValue) {
+    if (mSrcAttrStream) {
+      nsGkAtoms::none->ToString(aValue);
+      return;
+    }
+    GetEnumAttr(nsGkAtoms::preload, nullptr, aValue);
+  }
+  void SetPreload(const nsAString& aValue, ErrorResult& aRv) {
+    if (mSrcAttrStream) {
+      return;
+    }
+    SetHTMLAttr(nsGkAtoms::preload, aValue, aRv);
+  }
+
+  already_AddRefed<TimeRanges> Buffered() const;
+
+  void Load();
+
+  void CanPlayType(const nsAString& aType, nsAString& aResult);
+
+  uint16_t ReadyState() const { return mReadyState; }
+
+  bool Seeking() const;
+
+  double CurrentTime() const;
+
+  void SetCurrentTime(double aCurrentTime, ErrorResult& aRv);
+  void SetCurrentTime(double aCurrentTime) {
+    SetCurrentTime(aCurrentTime, IgnoreErrors());
+  }
+
+  void FastSeek(double aTime, ErrorResult& aRv);
+
+  already_AddRefed<Promise> SeekToNextFrame(ErrorResult& aRv);
+
+  double Duration() const;
+
+  bool HasAudio() const { return mMediaInfo.HasAudio(); }
+
+  virtual bool IsVideo() const { return false; }
+
+  bool HasVideo() const { return mMediaInfo.HasVideo(); }
+
+  bool IsEncrypted() const override { return mIsEncrypted; }
+
+#ifdef MOZ_WMF_CDM
+  bool IsUsingWMFCDM() const override;
+#endif
+
+  bool Paused() const { return mPaused; }
+
+  double DefaultPlaybackRate() const {
+    if (mSrcAttrStream) {
+      return 1.0;
+    }
+    return mDefaultPlaybackRate;
+  }
+
+  void SetDefaultPlaybackRate(double aDefaultPlaybackRate, ErrorResult& aRv);
+
+  double PlaybackRate() const {
+    if (mSrcAttrStream) {
+      return 1.0;
+    }
+    return mPlaybackRate;
+  }
+
+  void SetPlaybackRate(double aPlaybackRate, ErrorResult& aRv);
+
+  already_AddRefed<TimeRanges> Played();
+
+  already_AddRefed<TimeRanges> Seekable() const;
+
+  bool Ended();
+
+  bool Autoplay() const { return GetBoolAttr(nsGkAtoms::autoplay); }
+
+  void SetAutoplay(bool aValue, ErrorResult& aRv) {
+    SetHTMLBoolAttr(nsGkAtoms::autoplay, aValue, aRv);
+  }
+
+  bool Loop() const { return GetBoolAttr(nsGkAtoms::loop); }
+
+  void SetLoop(bool aValue, ErrorResult& aRv) {
+    SetHTMLBoolAttr(nsGkAtoms::loop, aValue, aRv);
+  }
+
+  already_AddRefed<Promise> Play(ErrorResult& aRv);
+  void Play() {
+    IgnoredErrorResult dummy;
+    RefPtr<Promise> toBeIgnored = Play(dummy);
+  }
+
+  void Pause(ErrorResult& aRv);
+  void Pause() { Pause(IgnoreErrors()); }
+
+  bool Controls() const { return GetBoolAttr(nsGkAtoms::controls); }
+
+  void SetControls(bool aValue, ErrorResult& aRv) {
+    SetHTMLBoolAttr(nsGkAtoms::controls, aValue, aRv);
+  }
+
+  double Volume() const { return mVolume; }
+
+  void SetVolume(double aVolume, ErrorResult& aRv);
+
+  bool Muted() const { return mMuted & MUTED_BY_CONTENT; }
+  void SetMuted(bool aMuted);
+
+  bool DefaultMuted() const { return GetBoolAttr(nsGkAtoms::muted); }
+
+  void SetDefaultMuted(bool aMuted, ErrorResult& aRv) {
+    SetHTMLBoolAttr(nsGkAtoms::muted, aMuted, aRv);
+  }
+
+  bool MozAllowCasting() const { return mAllowCasting; }
+
+  void SetMozAllowCasting(bool aShow) { mAllowCasting = aShow; }
+
+  bool MozIsCasting() const { return mIsCasting; }
+
+  void SetMozIsCasting(bool aShow) { mIsCasting = aShow; }
+
+  // Returns whether a call to Play() would be rejected with NotAllowedError.
+  // This assumes "worst case" for unknowns. So if prompting for permission is
+  // enabled and no permission is stored, this behaves as if the user would
+  // opt to block.
+  bool AllowedToPlay() const;
+
+  already_AddRefed<MediaSource> GetMozMediaSourceObject() const;
+
+  // Returns a promise which will be resolved after collecting debugging
+  // data from decoder/reader/MDSM. Used for debugging purposes.
+  already_AddRefed<Promise> MozRequestDebugInfo(ErrorResult& aRv);
+
+  // Enables DecoderDoctorLogger logging. Used for debugging purposes.
+  static void MozEnableDebugLog(const GlobalObject&);
+
+  // Returns a promise which will be resolved after collecting debugging
+  // log associated with this element. Used for debugging purposes.
+  already_AddRefed<Promise> MozRequestDebugLog(ErrorResult& aRv);
+
+  // For use by mochitests. Enabling pref "media.test.video-suspend"
+  void SetVisible(bool aVisible);
+
+  // For use by mochitests. Enabling pref "media.test.video-suspend"
+  bool HasSuspendTaint() const;
+
+  // For use by mochitests.
+  bool IsVideoDecodingSuspended() const;
+
+  // These functions return accumulated time, which are used for the telemetry
+  // usage. Return -1 for error.
+  double TotalVideoPlayTime() const;
+  double TotalVideoHDRPlayTime() const;
+  double VisiblePlayTime() const;
+  double InvisiblePlayTime() const;
+  double VideoDecodeSuspendedTime() const;
+  double TotalAudioPlayTime() const;
+  double AudiblePlayTime() const;
+  double InaudiblePlayTime() const;
+  double MutedPlayTime() const;
+
+  // Test methods for decoder doctor.
+  void SetFormatDiagnosticsReportForMimeType(const nsAString& aMimeType,
+                                             DecoderDoctorReportType aType);
+  void SetDecodeError(const nsAString& aError, ErrorResult& aRv);
+  void SetAudioSinkFailedStartup();
+
+  // Synchronously, return the next video frame and mark the element unable to
+  // participate in decode suspending.
+  //
+  // This function is synchronous for cases where decoding has been suspended
+  // and JS needs a frame to use in, eg., nsLayoutUtils::SurfaceFromElement()
+  // via drawImage().
+  already_AddRefed<layers::Image> GetCurrentImage();
+
+  already_AddRefed<DOMMediaStream> GetSrcObject() const;
+  void SetSrcObject(DOMMediaStream& aValue);
+  void SetSrcObject(DOMMediaStream* aValue);
+
+  bool PreservesPitch() const { return mPreservesPitch; }
+  void SetPreservesPitch(bool aPreservesPitch);
+
+  MediaKeys* GetMediaKeys() const;
+
+  already_AddRefed<Promise> SetMediaKeys(MediaKeys* mediaKeys,
+                                         ErrorResult& aRv);
+
+  mozilla::dom::EventHandlerNonNull* GetOnencrypted();
+  void SetOnencrypted(mozilla::dom::EventHandlerNonNull* aCallback);
+
+  mozilla::dom::EventHandlerNonNull* GetOnwaitingforkey();
+  void SetOnwaitingforkey(mozilla::dom::EventHandlerNonNull* aCallback);
+
+  void DispatchEncrypted(const nsTArray<uint8_t>& aInitData,
+                         const nsAString& aInitDataType) override;
+
+  bool IsEventAttributeNameInternal(nsAtom* aName) override;
+
+  bool ContainsRestrictedContent() const;
+
+  void NotifyWaitingForKey() override;
+
+  already_AddRefed<DOMMediaStream> CaptureAudio(ErrorResult& aRv,
+                                                MediaTrackGraph* aGraph);
+
+  already_AddRefed<DOMMediaStream> MozCaptureStream(ErrorResult& aRv);
+
+  already_AddRefed<DOMMediaStream> MozCaptureStreamUntilEnded(ErrorResult& aRv);
+
+  bool MozAudioCaptured() const { return mAudioCaptured; }
+
+  void MozGetMetadata(JSContext* aCx, JS::MutableHandle<JSObject*> aResult,
+                      ErrorResult& aRv);
+
+  double MozFragmentEnd();
+
+  AudioTrackList* AudioTracks();
+
+  VideoTrackList* VideoTracks();
+
+  TextTrackList* GetTextTracks();
+
+  already_AddRefed<TextTrack> AddTextTrack(TextTrackKind aKind,
+                                           const nsAString& aLabel,
+                                           const nsAString& aLanguage);
+
+  void AddTextTrack(TextTrack* aTextTrack) {
+    GetOrCreateTextTrackManager()->AddTextTrack(aTextTrack);
+  }
+
+  void RemoveTextTrack(TextTrack* aTextTrack, bool aPendingListOnly = false) {
+    if (mTextTrackManager) {
+      mTextTrackManager->RemoveTextTrack(aTextTrack, aPendingListOnly);
+    }
+  }
+
+  void NotifyCueAdded(TextTrackCue& aCue) {
+    if (mTextTrackManager) {
+      mTextTrackManager->NotifyCueAdded(aCue);
+    }
+  }
+  void NotifyCueRemoved(TextTrackCue& aCue) {
+    if (mTextTrackManager) {
+      mTextTrackManager->NotifyCueRemoved(aCue);
+    }
+  }
+  void NotifyCueUpdated(TextTrackCue* aCue) {
+    if (mTextTrackManager) {
+      mTextTrackManager->NotifyCueUpdated(aCue);
+    }
+  }
+
+  void NotifyCueDisplayStatesChanged();
+
+  bool IsBlessed() const { return mIsBlessed; }
+
+  // A method to check whether we are currently playing.
+  bool IsCurrentlyPlaying() const;
+
+  // Returns true if the media element is being destroyed. Used in
+  // dormancy checks to prevent dormant processing for an element
+  // that will soon be gone.
+  bool IsBeingDestroyed();
+
+  virtual void OnVisibilityChange(Visibility aNewVisibility);
+
+  // Begin testing only methods
+  float ComputedVolume() const;
+  bool ComputedMuted() const;
+
+  // Return true if the media has been suspended media due to an inactive
+  // document or prohibiting by the docshell.
+  bool IsSuspendedByInactiveDocOrDocShell() const;
+  // End testing only methods
+
+  void SetMediaInfo(const MediaInfo& aInfo);
+  MediaInfo GetMediaInfo() const override;
+
+  // Gives access to the decoder's frame statistics, if present.
+  FrameStatistics* GetFrameStatistics() const override;
+
+  void DispatchAsyncTestingEvent(const nsAString& aName) override;
+
+  AbstractThread* AbstractMainThread() const final;
+
+  // Log the usage of a {visible / invisible} video element as
+  // the source of {drawImage(), createPattern(), createImageBitmap() and
+  // captureStream()} APIs. This function can be used to collect telemetries for
+  // bug 1352007.
+  enum class CallerAPI {
+    DRAW_IMAGE,
+    CREATE_PATTERN,
+    CREATE_IMAGEBITMAP,
+    CAPTURE_STREAM,
+    CREATE_VIDEOFRAME,
+  };
+  void LogVisibility(CallerAPI aAPI);
+
+  Document* GetDocument() const override;
+
+  already_AddRefed<GMPCrashHelper> CreateGMPCrashHelper() override;
+
+  // Set the sink id (of the output device) that the audio will play. If aSinkId
+  // is empty the default device will be set.
+  already_AddRefed<Promise> SetSinkId(const nsAString& aSinkId,
+                                      ErrorResult& aRv);
+  // Get the sink id of the device that audio is being played. Initial value is
+  // empty and the default device is being used.
+  void GetSinkId(nsString& aSinkId) const {
+    MOZ_ASSERT(NS_IsMainThread());
+    aSinkId = mSink.first;
+  }
+
+  // This is used to notify MediaElementAudioSourceNode that media element is
+  // allowed to play when media element is used as a source for web audio, so
+  // that we can start AudioContext if it was not allowed to start.
+  RefPtr<GenericNonExclusivePromise> GetAllowedToPlayPromise();
+
+  bool GetShowPosterFlag() const { return mShowPoster; }
+
+  bool IsAudible() const;
+
+  // Return key system in use if we have one, otherwise return nothing.
+  Maybe<nsAutoString> GetKeySystem() const override;
+
+ protected:
+  virtual ~HTMLMediaElement();
+
+  class AudioChannelAgentCallback;
+  class ChannelLoader;
+  class ErrorSink;
+  class MediaElementTrackSource;
+  class MediaLoadListener;
+  class MediaStreamRenderer;
+  class MediaStreamTrackListener;
+  class ShutdownObserver;
+  class TitleChangeObserver;
+  class MediaControlKeyListener;
+
+  MediaDecoderOwner::NextFrameStatus NextFrameStatus();
+
+  void SetDecoder(MediaDecoder* aDecoder);
+
+  void PlayInternal(bool aHandlingUserInput);
+
+  // See spec, https://html.spec.whatwg.org/#internal-pause-steps
+  void PauseInternal();
+
+  /** Use this method to change the mReadyState member, so required
+   * events can be fired.
+   */
+  void ChangeReadyState(nsMediaReadyState aState);
+
+  /**
+   * Use this method to change the mNetworkState member, so required
+   * actions will be taken during the transition.
+   */
+  void ChangeNetworkState(nsMediaNetworkState aState);
+
+  /**
+   * The MediaElement will be responsible for creating and releasing the audio
+   * wakelock depending on the playing and audible state.
+   */
+  virtual void WakeLockRelease();
+  virtual void UpdateWakeLock();
+
+  void CreateAudioWakeLockIfNeeded();
+  void ReleaseAudioWakeLockIfExists();
+  RefPtr<WakeLock> mWakeLock;
+
+  /**
+   * Logs a warning message to the web console to report various failures.
+   * aMsg is the localized message identifier, aParams is the parameters to
+   * be substituted into the localized message, and aParamCount is the number
+   * of parameters in aParams.
+   */
+  void ReportLoadError(const char* aMsg, const nsTArray<nsString>& aParams =
+                                             nsTArray<nsString>());
+
+  /**
+   * Log message to web console.
+   */
+  void ReportToConsole(
+      uint32_t aErrorFlags, const char* aMsg,
+      const nsTArray<nsString>& aParams = nsTArray<nsString>()) const;
+
+  /**
+   * Changes mHasPlayedOrSeeked to aValue. If mHasPlayedOrSeeked changes
+   * we'll force a reflow so that the video frame gets reflowed to reflect
+   * the poster hiding or showing immediately.
+   */
+  void SetPlayedOrSeeked(bool aValue);
+
+  /**
+   * Initialize the media element for playback of aStream
+   */
+  void SetupSrcMediaStreamPlayback(DOMMediaStream* aStream);
+  /**
+   * Stop playback on mSrcStream.
+   */
+  void EndSrcMediaStreamPlayback();
+  /**
+   * Ensure we're playing mSrcStream if and only if we're not paused.
+   */
+  enum { REMOVING_SRC_STREAM = 0x1 };
+  void UpdateSrcMediaStreamPlaying(uint32_t aFlags = 0);
+
+  /**
+   * Ensure currentTime progresses if and only if we're potentially playing
+   * mSrcStream. Called by the watch manager while we're playing mSrcStream, and
+   * one of the inputs to the potentially playing algorithm changes.
+   */
+  void UpdateSrcStreamPotentiallyPlaying();
+
+  /**
+   * mSrcStream's graph's CurrentTime() has been updated. It might be time to
+   * fire "timeupdate".
+   */
+  void UpdateSrcStreamTime();
+
+  /**
+   * Called after a tail dispatch when playback of mSrcStream ended, to comply
+   * with the spec where we must start reporting true for the ended attribute
+   * after the event loop returns to step 1. A MediaStream could otherwise be
+   * manipulated to end a HTMLMediaElement synchronously.
+   */
+  void UpdateSrcStreamReportPlaybackEnded();
+
+  /**
+   * Called by our DOMMediaStream::TrackListener when a new MediaStreamTrack has
+   * been added to the playback stream of |mSrcStream|.
+   */
+  void NotifyMediaStreamTrackAdded(const RefPtr<MediaStreamTrack>& aTrack);
+
+  /**
+   * Called by our DOMMediaStream::TrackListener when a MediaStreamTrack in
+   * |mSrcStream|'s playback stream has ended.
+   */
+  void NotifyMediaStreamTrackRemoved(const RefPtr<MediaStreamTrack>& aTrack);
+
+  /**
+   * Convenience method to get in a single list all enabled AudioTracks and, if
+   * this is a video element, the selected VideoTrack.
+   */
+  void GetAllEnabledMediaTracks(nsTArray<RefPtr<MediaTrack>>& aTracks);
+
+  /**
+   * Enables or disables all tracks forwarded from mSrcStream to all
+   * OutputMediaStreams. We do this for muting the tracks when pausing,
+   * and unmuting when playing the media element again.
+   */
+  void SetCapturedOutputStreamsEnabled(bool aEnabled);
+
+  /**
+   * Returns true if output tracks should be muted, based on the state of this
+   * media element.
+   */
+  enum class OutputMuteState { Muted, Unmuted };
+  OutputMuteState OutputTracksMuted();
+
+  /**
+   * Sets the muted state of all output track sources. They are muted when we're
+   * paused and unmuted otherwise.
+   */
+  void UpdateOutputTracksMuting();
+
+  /**
+   * Create a new MediaStreamTrack for the TrackSource corresponding to aTrack
+   * and add it to the DOMMediaStream in aOutputStream. This automatically sets
+   * the output track to enabled or disabled depending on our current playing
+   * state.
+   */
+  enum class AddTrackMode { ASYNC, SYNC };
+  void AddOutputTrackSourceToOutputStream(
+      MediaElementTrackSource* aSource, OutputMediaStream& aOutputStream,
+      AddTrackMode aMode = AddTrackMode::ASYNC);
+
+  /**
+   * Creates output track sources when this media element is captured, tracks
+   * exist, playback is not ended and readyState is >= HAVE_METADATA.
+   */
+  void UpdateOutputTrackSources();
+
+  /**
+   * Returns an DOMMediaStream containing the played contents of this
+   * element. When aBehavior is FINISH_WHEN_ENDED, when this element ends
+   * playback we will finish the stream and not play any more into it.  When
+   * aType is CONTINUE_WHEN_ENDED, ending playback does not finish the stream.
+   * The stream will never finish.
+   *
+   * When aType is CAPTURE_AUDIO, we stop playout of audio and instead route it
+   * to the DOMMediaStream. Volume and mute state will be applied to the audio
+   * reaching the stream. No video tracks will be captured in this case.
+   *
+   * aGraph may be null if the stream's tracks do not need to use a
+   * specific graph.
+   */
+  already_AddRefed<DOMMediaStream> CaptureStreamInternal(
+      StreamCaptureBehavior aFinishBehavior,
+      StreamCaptureType aStreamCaptureType, MediaTrackGraph* aGraph);
+
+  /**
+   * Initialize a decoder as a clone of an existing decoder in another
+   * element.
+   * mLoadingSrc must already be set.
+   */
+  nsresult InitializeDecoderAsClone(ChannelMediaDecoder* aOriginal);
+
+  /**
+   * Call Load() and FinishDecoderSetup() on the decoder. It also handle
+   * resource cloning if DecoderType is ChannelMediaDecoder.
+   */
+  template <typename DecoderType, typename... LoadArgs>
+  nsresult SetupDecoder(DecoderType* aDecoder, LoadArgs&&... aArgs);
+
+  /**
+   * Initialize a decoder to load the given channel. The decoder's stream
+   * listener is returned via aListener.
+   * mLoadingSrc must already be set.
+   */
+  nsresult InitializeDecoderForChannel(nsIChannel* aChannel,
+                                       nsIStreamListener** aListener);
+
+  /**
+   * Finish setting up the decoder after Load() has been called on it.
+   * Called by InitializeDecoderForChannel/InitializeDecoderAsClone.
+   */
+  nsresult FinishDecoderSetup(MediaDecoder* aDecoder);
+
+  /**
+   * Call this after setting up mLoadingSrc and mDecoder.
+   */
+  void AddMediaElementToURITable();
+  /**
+   * Call this before modifying mLoadingSrc.
+   */
+  void RemoveMediaElementFromURITable();
+  /**
+   * Call this to find a media element with the same NodePrincipal and
+   * mLoadingSrc set to aURI, and with a decoder on which Load() has been
+   * called.
+   */
+  HTMLMediaElement* LookupMediaElementURITable(nsIURI* aURI);
+
+  /**
+   * Shutdown and clear mDecoder and maintain associated invariants.
+   */
+  void ShutdownDecoder();
+  /**
+   * Execute the initial steps of the load algorithm that ensure existing
+   * loads are aborted, the element is emptied, and a new load ID is
+   * created.
+   */
+  void AbortExistingLoads();
+
+  /**
+   * This is the dedicated media source failure steps.
+   * Called when all potential resources are exhausted. Changes network
+   * state to NETWORK_NO_SOURCE, and sends error event with code
+   * MEDIA_ERR_SRC_NOT_SUPPORTED.
+   */
+  void NoSupportedMediaSourceError(
+      const nsACString& aErrorDetails = nsCString());
+
+  /**
+   * Per spec, Failed with elements: Queue a task, using the DOM manipulation
+   * task source, to fire a simple event named error at the candidate element.
+   * So dispatch |QueueLoadFromSourceTask| to main thread to make sure the task
+   * will be executed later than loadstart event.
+   */
+  void DealWithFailedElement(nsIContent* aSourceElement);
+
+  /**
+   * Attempts to load resources from the <source> children. This is a
+   * substep of the resource selection algorithm. Do not call this directly,
+   * call QueueLoadFromSourceTask() instead.
+   */
+  void LoadFromSourceChildren();
+
+  /**
+   * Asynchronously awaits a stable state, and then causes
+   * LoadFromSourceChildren() to be called on the main threads' event loop.
+   */
+  void QueueLoadFromSourceTask();
+
+  /**
+   * Runs the media resource selection algorithm.
+   */
+  void SelectResource();
+
+  /**
+   * A wrapper function that allows us to cleanly reset flags after a call
+   * to SelectResource()
+   */
+  void SelectResourceWrapper();
+
+  /**
+   * Asynchronously awaits a stable state, and then causes SelectResource()
+   * to be run on the main thread's event loop.
+   */
+  void QueueSelectResourceTask();
+
+  /**
+   * When loading a new source on an existing media element, make sure to reset
+   * everything that is accessible using the media element API.
+   */
+  void ResetState();
+
+  /**
+   * The resource-fetch algorithm step of the load algorithm.
+   */
+  MediaResult LoadResource();
+
+  /**
+   * Selects the next <source> child from which to load a resource. Called
+   * during the resource selection algorithm. Stores the return value in
+   * mSourceLoadCandidate before returning.
+   */
+  HTMLSourceElement* GetNextSource();
+
+  /**
+   * Changes mDelayingLoadEvent, and will call BlockOnLoad()/UnblockOnLoad()
+   * on the owning document, so it can delay the load event firing.
+   */
+  void ChangeDelayLoadStatus(bool aDelay);
+
+  /**
+   * If we suspended downloading after the first frame, unsuspend now.
+   */
+  void StopSuspendingAfterFirstFrame();
+
+  /**
+   * Called when our channel is redirected to another channel.
+   * Updates our mChannel reference to aNewChannel.
+   */
+  nsresult OnChannelRedirect(nsIChannel* aChannel, nsIChannel* aNewChannel,
+                             uint32_t aFlags);
+
+  /**
+   * Call this to reevaluate whether we should be holding a self-reference.
+   */
+  void AddRemoveSelfReference();
+
+  /**
+   * Called when "xpcom-shutdown" event is received.
+   */
+  void NotifyShutdownEvent();
+
+  /**
+   * Possible values of the 'preload' attribute.
+   */
+  enum PreloadAttrValue : uint8_t {
+    PRELOAD_ATTR_EMPTY,     // set to ""
+    PRELOAD_ATTR_NONE,      // set to "none"
+    PRELOAD_ATTR_METADATA,  // set to "metadata"
+    PRELOAD_ATTR_AUTO       // set to "auto"
+  };
+
+  /**
+   * The preloading action to perform. These dictate how we react to the
+   * preload attribute. See mPreloadAction.
+   */
+  enum PreloadAction {
+    PRELOAD_UNDEFINED = 0,  // not determined - used only for initialization
+    PRELOAD_NONE = 1,       // do not preload
+    PRELOAD_METADATA = 2,   // preload only the metadata (and first frame)
+    PRELOAD_ENOUGH = 3      // preload enough data to allow uninterrupted
+                            // playback
+  };
+
+  /**
+   * The guts of Load(). Load() acts as a wrapper around this which sets
+   * mIsDoingExplicitLoad to true so that when script calls 'load()'
+   * preload-none will be automatically upgraded to preload-metadata.
+   */
+  void DoLoad();
+
+  /**
+   * Suspends the load of mLoadingSrc, so that it can be resumed later
+   * by ResumeLoad(). This is called when we have a media with a 'preload'
+   * attribute value of 'none', during the resource selection algorithm.
+   */
+  void SuspendLoad();
+
+  /**
+   * Resumes a previously suspended load (suspended by SuspendLoad(uri)).
+   * Will continue running the resource selection algorithm.
+   * Sets mPreloadAction to aAction.
+   */
+  void ResumeLoad(PreloadAction aAction);
+
+  /**
+   * Handle a change to the preload attribute. Should be called whenever the
+   * value (or presence) of the preload attribute changes. The change in
+   * attribute value may cause a change in the mPreloadAction of this
+   * element. If there is a change then this method will initiate any
+   * behaviour that is necessary to implement the action.
+   */
+  void UpdatePreloadAction();
+
+  /**
+   * Fire progress events if needed according to the time and byte constraints
+   * outlined in the specification. aHaveNewProgress is true if progress has
+   * just been detected.  Otherwise the method is called as a result of the
+   * progress timer.
+   */
+  void CheckProgress(bool aHaveNewProgress);
+  static void ProgressTimerCallback(nsITimer* aTimer, void* aClosure);
+  /**
+   * Start timer to update download progress.
+   */
+  void StartProgressTimer();
+  /**
+   * Start sending progress and/or stalled events.
+   */
+  void StartProgress();
+  /**
+   * Stop progress information timer and events.
+   */
+  void StopProgress();
+
+  /**
+   * Dispatches an error event to a child source element.
+   */
+  void DispatchAsyncSourceError(nsIContent* aSourceElement);
+
+  /**
+   * Resets the media element for an error condition as per aErrorCode.
+   * aErrorCode must be one of WebIDL HTMLMediaElement error codes.
+   */
+  void Error(uint16_t aErrorCode,
+             const nsACString& aErrorDetails = nsCString());
+
+  /**
+   * Returns the URL spec of the currentSrc.
+   **/
+  void GetCurrentSpec(nsCString& aString);
+
+  /**
+   * Process any media fragment entries in the URI
+   */
+  void ProcessMediaFragmentURI();
+
+  /**
+   * Mute or unmute the audio and change the value that the |muted| map.
+   */
+  void SetMutedInternal(uint32_t aMuted);
+  /**
+   * Update the volume of the output audio stream to match the element's
+   * current mMuted/mVolume/mAudioChannelFaded state.
+   */
+  void SetVolumeInternal();
+
+  /**
+   * Suspend or resume element playback and resource download.  When we suspend
+   * playback, event delivery would also be suspended (and events queued) until
+   * the element is resumed.
+   */
+  void SuspendOrResumeElement(bool aSuspendElement);
+
+  // Get the HTMLMediaElement object if the decoder is being used from an
+  // HTML media element, and null otherwise.
+  HTMLMediaElement* GetMediaElement() final { return this; }
+
+  // Return true if decoding should be paused
+  bool GetPaused() final { return Paused(); }
+
+  // Seeks to aTime seconds. aSeekType can be Exact to seek to exactly the
+  // seek target, or PrevSyncPoint if a quicker but less precise seek is
+  // desired, and we'll seek to the sync point (keyframe and/or start of the
+  // next block of audio samples) preceeding seek target.
+  void Seek(double aTime, SeekTarget::Type aSeekType, ErrorResult& aRv);
+
+  // Update the audio channel playing state
+  void UpdateAudioChannelPlayingState();
+
+  // Adds to the element's list of pending text tracks each text track
+  // in the element's list of text tracks whose text track mode is not disabled
+  // and whose text track readiness state is loading.
+  void PopulatePendingTextTrackList();
+
+  // Gets a reference to the MediaElement's TextTrackManager. If the
+  // MediaElement doesn't yet have one then it will create it.
+  TextTrackManager* GetOrCreateTextTrackManager();
+
+  // Recomputes ready state and fires events as necessary based on current
+  // state.
+  void UpdateReadyStateInternal();
+
+  // Create or destroy the captured stream.
+  void AudioCaptureTrackChange(bool aCapture);
+
+  // If the network state is empty and then we would trigger DoLoad().
+  void MaybeDoLoad();
+
+  // Anything we need to check after played success and not related with spec.
+  void UpdateCustomPolicyAfterPlayed();
+
+  // Returns a StreamCaptureType populated with the right bits, depending on the
+  // tracks this HTMLMediaElement has.
+  StreamCaptureType CaptureTypeForElement();
+
+  // True if this element can be captured, false otherwise.
+  bool CanBeCaptured(StreamCaptureType aCaptureType);
+
+  using nsGenericHTMLElement::DispatchEvent;
+  // For nsAsyncEventRunner.
+  nsresult DispatchEvent(const nsAString& aName);
+
+  already_AddRefed<nsMediaEventRunner> GetEventRunner(
+      const nsAString& aName, EventFlag aFlag = EventFlag::eNone);
+
+  // This method moves the mPendingPlayPromises into a temperate object. So the
+  // mPendingPlayPromises is cleared after this method call.
+  nsTArray<RefPtr<PlayPromise>> TakePendingPlayPromises();
+
+  // This method snapshots the mPendingPlayPromises by TakePendingPlayPromises()
+  // and queues a task to resolve them.
+  void AsyncResolvePendingPlayPromises();
+
+  // This method snapshots the mPendingPlayPromises by TakePendingPlayPromises()
+  // and queues a task to reject them.
+  void AsyncRejectPendingPlayPromises(nsresult aError);
+
+  // This method snapshots the mPendingPlayPromises by TakePendingPlayPromises()
+  // and queues a task to resolve them also to dispatch a "playing" event.
+  void NotifyAboutPlaying();
+
+  already_AddRefed<Promise> CreateDOMPromise(ErrorResult& aRv) const;
+
+  // Pass information for deciding the video decode mode to decoder.
+  void NotifyDecoderActivityChanges() const;
+
+  // Constructs an AudioTrack in mAudioTrackList if aInfo reports that audio is
+  // available, and a VideoTrack in mVideoTrackList if aInfo reports that video
+  // is available.
+  void ConstructMediaTracks(const MediaInfo* aInfo);
+
+  // Removes all MediaTracks from mAudioTrackList and mVideoTrackList and fires
+  // "removetrack" on the lists accordingly.
+  // Note that by spec, this should not fire "removetrack". However, it appears
+  // other user agents do, per
+  // https://wpt.fyi/results/media-source/mediasource-avtracks.html.
+  void RemoveMediaTracks();
+
+  // Mark the decoder owned by the element as tainted so that the
+  // suspend-video-decoder is disabled.
+  void MarkAsTainted();
+
+  virtual void AfterSetAttr(int32_t aNameSpaceID, nsAtom* aName,
+                            const nsAttrValue* aValue,
+                            const nsAttrValue* aOldValue,
+                            nsIPrincipal* aMaybeScriptedPrincipal,
+                            bool aNotify) override;
+  virtual void OnAttrSetButNotChanged(int32_t aNamespaceID, nsAtom* aName,
+                                      const nsAttrValueOrString& aValue,
+                                      bool aNotify) override;
+
+  bool DetachExistingMediaKeys();
+  bool TryRemoveMediaKeysAssociation();
+  void RemoveMediaKeys();
+  bool AttachNewMediaKeys();
+  bool TryMakeAssociationWithCDM(CDMProxy* aProxy);
+  void MakeAssociationWithCDMResolved();
+  void SetCDMProxyFailure(const MediaResult& aResult);
+  void ResetSetMediaKeysTempVariables();
+
+  void PauseIfShouldNotBePlaying();
+
+  WatchManager<HTMLMediaElement> mWatchManager;
+
+  // When the play is not allowed, dispatch related events which are used for
+  // testing or changing control UI.
+  void DispatchEventsWhenPlayWasNotAllowed();
+
+  // When the doc is blocked permanantly, we would dispatch event to notify
+  // front-end side to show blocking icon.
+  void MaybeNotifyAutoplayBlocked();
+
+  // Dispatch event for video control when video gets blocked in order to show
+  // the click-to-play icon.
+  void DispatchBlockEventForVideoControl();
+
+  // When playing state change, we have to notify MediaControl in the chrome
+  // process in order to keep its playing state correct.
+  void NotifyMediaControlPlaybackStateChanged();
+
+  // Clear the timer when we want to continue listening to the media control
+  // key events.
+  void ClearStopMediaControlTimerIfNeeded();
+
+  // Sets a secondary renderer for mSrcStream, so this media element can be
+  // rendered in Picture-in-Picture mode when playing a MediaStream. A null
+  // aContainer will unset the secondary renderer. aFirstFrameOutput allows
+  // for injecting a listener of the callers choice for rendering the first
+  // frame.
+  void SetSecondaryMediaStreamRenderer(
+      VideoFrameContainer* aContainer,
+      FirstFrameVideoOutput* aFirstFrameOutput = nullptr);
+
+  // This function is used to update the status of media control when the media
+  // changes its status of being used in the Picture-in-Picture mode.
+  void UpdateMediaControlAfterPictureInPictureModeChanged();
+
+  // The current decoder. Load() has been called on this decoder.
+  // At most one of mDecoder and mSrcStream can be non-null.
+  RefPtr<MediaDecoder> mDecoder;
+
+  // A reference to the VideoFrameContainer which contains the current frame
+  // of video to display.
+  RefPtr<VideoFrameContainer> mVideoFrameContainer;
+
+  // Holds a reference to the MediaStream that has been set in the src
+  // attribute.
+  RefPtr<DOMMediaStream> mSrcAttrStream;
+
+  // Holds the triggering principal for the src attribute.
+  nsCOMPtr<nsIPrincipal> mSrcAttrTriggeringPrincipal;
+
+  // Holds a reference to the MediaStream that we're actually playing.
+  // At most one of mDecoder and mSrcStream can be non-null.
+  RefPtr<DOMMediaStream> mSrcStream;
+
+  // The MediaStreamRenderer handles rendering of our selected video track, and
+  // enabled audio tracks, while mSrcStream is set.
+  RefPtr<MediaStreamRenderer> mMediaStreamRenderer;
+
+  // The secondary MediaStreamRenderer handles rendering of our selected video
+  // track to a secondary VideoFrameContainer, while mSrcStream is set.
+  RefPtr<MediaStreamRenderer> mSecondaryMediaStreamRenderer;
+
+  // True once PlaybackEnded() is called and we're playing a MediaStream.
+  // Reset to false if we start playing mSrcStream again.
+  Watchable<bool> mSrcStreamPlaybackEnded = {
+      false, "HTMLMediaElement::mSrcStreamPlaybackEnded"};
+
+  // Mirrors mSrcStreamPlaybackEnded after a tail dispatch when set to true,
+  // but may be be forced to false directly. To accomodate when an application
+  // ends playback synchronously by manipulating mSrcStream or its tracks,
+  // e.g., through MediaStream.removeTrack(), or MediaStreamTrack.stop().
+  bool mSrcStreamReportPlaybackEnded = false;
+
+  // Holds a reference to the stream connecting this stream to the window
+  // capture sink.
+  UniquePtr<MediaStreamWindowCapturer> mStreamWindowCapturer;
+
+  // Holds references to the DOM wrappers for the MediaStreams that we're
+  // writing to.
+  nsTArray<OutputMediaStream> mOutputStreams;
+
+  // Mapping for output tracks, from dom::MediaTrack ids to the
+  // MediaElementTrackSource that represents the source of all corresponding
+  // MediaStreamTracks captured from this element.
+  nsRefPtrHashtable<nsStringHashKey, MediaElementTrackSource>
+      mOutputTrackSources;
+
+  // The currently selected video stream track.
+  RefPtr<VideoStreamTrack> mSelectedVideoStreamTrack;
+
+  const RefPtr<ShutdownObserver> mShutdownObserver;
+
+  const RefPtr<TitleChangeObserver> mTitleChangeObserver;
+
+  // Holds a reference to the MediaSource, if any, referenced by the src
+  // attribute on the media element.
+  RefPtr<MediaSource> mSrcMediaSource;
+
+  // Holds a reference to the MediaSource supplying data for playback.  This
+  // may either match mSrcMediaSource or come from Source element children.
+  // This is set when and only when mLoadingSrc corresponds to an object url
+  // that resolved to a MediaSource.
+  RefPtr<MediaSource> mMediaSource;
+
+  RefPtr<ChannelLoader> mChannelLoader;
+
+  // Points to the child source elements, used to iterate through the children
+  // when selecting a resource to load.  This is the previous sibling of the
+  // child considered the current 'candidate' in:
+  // https://html.spec.whatwg.org/multipage/media.html#concept-media-load-algorithm
+  //
+  // mSourcePointer == nullptr, we will next try to load |GetFirstChild()|.
+  // mSourcePointer == GetLastChild(), we've exhausted all sources, waiting
+  // for new elements to be appended.
+  nsCOMPtr<nsIContent> mSourcePointer;
+
+  // Points to the document whose load we're blocking. This is the document
+  // we're bound to when loading starts.
+  nsCOMPtr<Document> mLoadBlockedDoc;
+
+  // This is used to help us block/resume the event delivery.
+  class EventBlocker;
+  RefPtr<EventBlocker> mEventBlocker;
+
+  // Media loading flags. See:
+  //   http://www.whatwg.org/specs/web-apps/current-work/#video)
+  nsMediaNetworkState mNetworkState = HTMLMediaElement_Binding::NETWORK_EMPTY;
+  Watchable<nsMediaReadyState> mReadyState = {
+      HTMLMediaElement_Binding::HAVE_NOTHING, "HTMLMediaElement::mReadyState"};
+
+  enum LoadAlgorithmState {
+    // No load algorithm instance is waiting for a source to be added to the
+    // media in order to continue loading.
+    NOT_WAITING,
+    // We've run the load algorithm, and we tried all source children of the
+    // media element, and failed to load any successfully. We're waiting for
+    // another source element to be added to the media element, and will try
+    // to load any such element when its added.
+    WAITING_FOR_SOURCE
+  };
+
+  // The current media load ID. This is incremented every time we start a
+  // new load. Async events note the ID when they're first sent, and only fire
+  // if the ID is unchanged when they come to fire.
+  uint32_t mCurrentLoadID = 0;
+
+  // Denotes the waiting state of a load algorithm instance. When the load
+  // algorithm is waiting for a source element child to be added, this is set
+  // to WAITING_FOR_SOURCE, otherwise it's NOT_WAITING.
+  LoadAlgorithmState mLoadWaitStatus = NOT_WAITING;
+
+  // Current audio volume
+  double mVolume = 1.0;
+
+  // True if the audio track is not silent.
+  bool mIsAudioTrackAudible = false;
+
+  enum MutedReasons {
+    MUTED_BY_CONTENT = 0x01,
+    MUTED_BY_INVALID_PLAYBACK_RATE = 0x02,
+    MUTED_BY_AUDIO_CHANNEL = 0x04,
+    MUTED_BY_AUDIO_TRACK = 0x08
+  };
+
+  uint32_t mMuted = 0;
+
+  UniquePtr<const MetadataTags> mTags;
+
+  // URI of the resource we're attempting to load. This stores the value we
+  // return in the currentSrc attribute. Use GetCurrentSrc() to access the
+  // currentSrc attribute.
+  // This is always the original URL we're trying to load --- before
+  // redirects etc.
+  nsCOMPtr<nsIURI> mLoadingSrc;
+
+  // The triggering principal for the current source.
+  nsCOMPtr<nsIPrincipal> mLoadingSrcTriggeringPrincipal;
+
+  // Stores the current preload action for this element. Initially set to
+  // PRELOAD_UNDEFINED, its value is changed by calling
+  // UpdatePreloadAction().
+  PreloadAction mPreloadAction = PRELOAD_UNDEFINED;
+
+  // Time that the last timeupdate event was queued. Read/Write from the
+  // main thread only.
+  TimeStamp mQueueTimeUpdateRunnerTime;
+
+  // Time that the last timeupdate event was fired. Read/Write from the
+  // main thread only.
+  TimeStamp mLastTimeUpdateDispatchTime;
+
+  // Time that the last progress event was fired. Read/Write from the
+  // main thread only.
+  TimeStamp mProgressTime;
+
+  // Time that data was last read from the media resource. Used for
+  // computing if the download has stalled and to rate limit progress events
+  // when data is arriving slower than PROGRESS_MS.
+  // Read/Write from the main thread only.
+  TimeStamp mDataTime;
+
+  // Media 'currentTime' value when the last timeupdate event was queued.
+  // Read/Write from the main thread only.
+  double mLastCurrentTime = 0.0;
+
+  // Logical start time of the media resource in seconds as obtained
+  // from any media fragments. A negative value indicates that no
+  // fragment time has been set. Read/Write from the main thread only.
+  double mFragmentStart = -1.0;
+
+  // Logical end time of the media resource in seconds as obtained
+  // from any media fragments. A negative value indicates that no
+  // fragment time has been set. Read/Write from the main thread only.
+  double mFragmentEnd = -1.0;
+
+  // The defaultPlaybackRate attribute gives the desired speed at which the
+  // media resource is to play, as a multiple of its intrinsic speed.
+  double mDefaultPlaybackRate = 1.0;
+
+  // The playbackRate attribute gives the speed at which the media resource
+  // plays, as a multiple of its intrinsic speed. If it is not equal to the
+  // defaultPlaybackRate, then the implication is that the user is using a
+  // feature such as fast forward or slow motion playback.
+  double mPlaybackRate = 1.0;
+
+  // True if pitch correction is applied when playbackRate is set to a
+  // non-intrinsic value.
+  bool mPreservesPitch = true;
+
+  // Reference to the source element last returned by GetNextSource().
+  // This is the child source element which we're trying to load from.
+  nsCOMPtr<nsIContent> mSourceLoadCandidate;
+
+  // Range of time played.
+  RefPtr<TimeRanges> mPlayed;
+
+  // Timer used for updating progress events.
+  nsCOMPtr<nsITimer> mProgressTimer;
+
+  // Encrypted Media Extension media keys.
+  RefPtr<MediaKeys> mMediaKeys;
+  RefPtr<MediaKeys> mIncomingMediaKeys;
+  // The dom promise is used for HTMLMediaElement::SetMediaKeys.
+  RefPtr<DetailedPromise> mSetMediaKeysDOMPromise;
+  // Used to indicate if the MediaKeys attaching operation is on-going or not.
+  bool mAttachingMediaKey = false;
+  MozPromiseRequestHolder<SetCDMPromise> mSetCDMRequest;
+
+  // Stores the time at the start of the current 'played' range.
+  double mCurrentPlayRangeStart = 1.0;
+
+  // True if loadeddata has been fired.
+  bool mLoadedDataFired = false;
+
+  // One of the factors determines whether a media element with 'autoplay'
+  // attribute is allowed to start playing.
+  // https://html.spec.whatwg.org/multipage/media.html#can-autoplay-flag
+  bool mCanAutoplayFlag = true;
+
+  // Playback of the video is paused either due to calling the
+  // 'Pause' method, or playback not yet having started.
+  Watchable<bool> mPaused = {true, "HTMLMediaElement::mPaused"};
+
+  // The following two fields are here for the private storage of the builtin
+  // video controls, and control 'casting' of the video to external devices
+  // (TVs, projectors etc.)
+  // True if casting is currently allowed
+  bool mAllowCasting = false;
+  // True if currently casting this video
+  bool mIsCasting = false;
+
+  // Set while there are some OutputMediaStreams this media element's enabled
+  // and selected tracks are captured into. When set, all tracks are captured
+  // into the graph of this dummy track.
+  // NB: This is a SharedDummyTrack to allow non-default graphs (AudioContexts
+  // with an explicit sampleRate defined) to capture this element. When
+  // cross-graph tracks are supported, this can become a bool.
+  Watchable<RefPtr<SharedDummyTrack>> mTracksCaptured;
+
+  // True if the sound is being captured.
+  bool mAudioCaptured = false;
+
+  // If TRUE then the media element was actively playing before the currently
+  // in progress seeking. If FALSE then the media element is either not seeking
+  // or was not actively playing before the current seek. Used to decide whether
+  // to raise the 'waiting' event as per 4.7.1.8 in HTML 5 specification.
+  bool mPlayingBeforeSeek = false;
+
+  // True if this element is suspended because the document is inactive or the
+  // inactive docshell is not allowing media to play.
+  bool mSuspendedByInactiveDocOrDocshell = false;
+
+  // True if we're running the "load()" method.
+  bool mIsRunningLoadMethod = false;
+
+  // True if we're running or waiting to run queued tasks due to an explicit
+  // call to "load()".
+  bool mIsDoingExplicitLoad = false;
+
+  // True if we're loading the resource from the child source elements.
+  bool mIsLoadingFromSourceChildren = false;
+
+  // True if we're delaying the "load" event. They are delayed until either
+  // an error occurs, or the first frame is loaded.
+  bool mDelayingLoadEvent = false;
+
+  // True when we've got a task queued to call SelectResource(),
+  // or while we're running SelectResource().
+  bool mIsRunningSelectResource = false;
+
+  // True when we already have select resource call queued
+  bool mHaveQueuedSelectResource = false;
+
+  // True if we suspended the decoder because we were paused,
+  // preloading metadata is enabled, autoplay was not enabled, and we loaded
+  // the first frame.
+  bool mSuspendedAfterFirstFrame = false;
+
+  // True if we are allowed to suspend the decoder because we were paused,
+  // preloading metdata was enabled, autoplay was not enabled, and we loaded
+  // the first frame.
+  bool mAllowSuspendAfterFirstFrame = true;
+
+  // True if we've played or completed a seek. We use this to determine
+  // when the poster frame should be shown.
+  bool mHasPlayedOrSeeked = false;
+
+  // True if we've added a reference to ourselves to keep the element
+  // alive while no-one is referencing it but the element may still fire
+  // events of its own accord.
+  bool mHasSelfReference = false;
+
+  // True if we've received a notification that the engine is shutting
+  // down.
+  bool mShuttingDown = false;
+
+  // True if we've suspended a load in the resource selection algorithm
+  // due to loading a preload:none media. When true, the resource we'll
+  // load when the user initiates either playback or an explicit load is
+  // stored in mPreloadURI.
+  bool mSuspendedForPreloadNone = false;
+
+  // True if we've connected mSrcStream to the media element output.
+  bool mSrcStreamIsPlaying = false;
+
+  // True if we should set nsIClassOfService::UrgentStart to the channel to
+  // get the response ASAP for better user responsiveness.
+  bool mUseUrgentStartForChannel = false;
+
+  // The CORS mode when loading the media element
+  CORSMode mCORSMode = CORS_NONE;
+
+  // Info about the played media.
+  MediaInfo mMediaInfo;
+
+  // True if the media has encryption information.
+  bool mIsEncrypted = false;
+
+  enum WaitingForKeyState {
+    NOT_WAITING_FOR_KEY = 0,
+    WAITING_FOR_KEY = 1,
+    WAITING_FOR_KEY_DISPATCHED = 2
+  };
+
+  // True when the CDM cannot decrypt the current block due to lacking a key.
+  // Note: the "waitingforkey" event is not dispatched until all decoded data
+  // has been rendered.
+  WaitingForKeyState mWaitingForKey = NOT_WAITING_FOR_KEY;
+
+  // Listens for waitingForKey events from the owned decoder.
+  MediaEventListener mWaitingForKeyListener;
+
+  // Init Data that needs to be sent in 'encrypted' events in MetadataLoaded().
+  EncryptionInfo mPendingEncryptedInitData;
+
+  // True if the media's channel's download has been suspended.
+  Watchable<bool> mDownloadSuspendedByCache = {
+      false, "HTMLMediaElement::mDownloadSuspendedByCache"};
+
+  // Disable the video playback by track selection. This flag might not be
+  // enough if we ever expand the ability of supporting multi-tracks video
+  // playback.
+  bool mDisableVideo = false;
+
+  RefPtr<TextTrackManager> mTextTrackManager;
+
+  RefPtr<AudioTrackList> mAudioTrackList;
+
+  RefPtr<VideoTrackList> mVideoTrackList;
+
+  UniquePtr<MediaStreamTrackListener> mMediaStreamTrackListener;
+
+  // The principal guarding mVideoFrameContainer access when playing a
+  // MediaStream.
+  nsCOMPtr<nsIPrincipal> mSrcStreamVideoPrincipal;
+
+  // True if the autoplay media was blocked because it hadn't loaded metadata
+  // yet.
+  bool mBlockedAsWithoutMetadata = false;
+
+  // This promise is used to notify MediaElementAudioSourceNode that media
+  // element is allowed to play when MediaElement is used as a source for web
+  // audio.
+  MozPromiseHolder<GenericNonExclusivePromise> mAllowedToPlayPromise;
+
+  // True if media has ever been blocked for autoplay, it's used to notify front
+  // end to show the correct blocking icon when the document goes back from
+  // bfcache.
+  bool mHasEverBeenBlockedForAutoplay = false;
+
+  // True if we have dispatched a task for text track changed, will be unset
+  // when we starts processing text track changed.
+  // https://html.spec.whatwg.org/multipage/media.html#pending-text-track-change-notification-flag
+  bool mPendingTextTrackChanged = false;
+
+ public:
+  // This function will be called whenever a text track that is in a media
+  // element's list of text tracks has its text track mode change value
+  void NotifyTextTrackModeChanged();
+
+ private:
+  friend class nsMediaEventRunner;
+  friend class nsResolveOrRejectPendingPlayPromisesRunner;
+
+  already_AddRefed<PlayPromise> CreatePlayPromise(ErrorResult& aRv) const;
+
+  virtual void MaybeBeginCloningVisually(){};
+
+  uint32_t GetPreloadDefault() const;
+  uint32_t GetPreloadDefaultAuto() const;
+
+  /**
+   * This function is called by AfterSetAttr and OnAttrSetButNotChanged.
+   * It will not be called if the value is being unset.
+   *
+   * @param aNamespaceID the namespace of the attr being set
+   * @param aName the localname of the attribute being set
+   * @param aNotify Whether we plan to notify document observers.
+   */
+  void AfterMaybeChangeAttr(int32_t aNamespaceID, nsAtom* aName, bool aNotify);
+
+  // True if Init() has been called after construction
+  bool mInitialized = false;
+
+  // True if user has called load(), seek() or element has started playing
+  // before. It's *only* use for `click-to-play` blocking autoplay policy.
+  // In addition, we would reset this once media aborts current load.
+  bool mIsBlessed = false;
+
+  // True if the first frame has been successfully loaded.
+  Watchable<bool> mFirstFrameLoaded = {false,
+                                       "HTMLMediaElement::mFirstFrameLoaded"};
+
+  // Media elements also have a default playback start position, which must
+  // initially be set to zero seconds. This time is used to allow the element to
+  // be seeked even before the media is loaded.
+  double mDefaultPlaybackStartPosition = 0.0;
+
+  // True if media element has been marked as 'tainted' and can't
+  // participate in video decoder suspending.
+  bool mHasSuspendTaint = false;
+
+  // True if media element has been forced into being considered 'hidden'.
+  // For use by mochitests. Enabling pref "media.test.video-suspend"
+  bool mForcedHidden = false;
+
+  Visibility mVisibilityState = Visibility::Untracked;
+
+  UniquePtr<ErrorSink> mErrorSink;
+
+  // This wrapper will handle all audio channel related stuffs, eg. the
+  // operations of tab audio indicator, Fennec's media control. Note:
+  // mAudioChannelWrapper might be null after GC happened.
+  RefPtr<AudioChannelAgentCallback> mAudioChannelWrapper;
+
+  // A list of pending play promises. The elements are pushed during the play()
+  // method call and are resolved/rejected during further playback steps.
+  nsTArray<RefPtr<PlayPromise>> mPendingPlayPromises;
+
+  // A list of already-dispatched but not yet run
+  // nsResolveOrRejectPendingPlayPromisesRunners.
+  // Runners whose Run() method is called remove themselves from this list.
+  // We keep track of these because the load algorithm resolves/rejects all
+  // already-dispatched pending play promises.
+  nsTArray<nsResolveOrRejectPendingPlayPromisesRunner*>
+      mPendingPlayPromisesRunners;
+
+  // A pending seek promise which is created at Seek() method call and is
+  // resolved/rejected at AsyncResolveSeekDOMPromiseIfExists()/
+  // AsyncRejectSeekDOMPromiseIfExists() methods.
+  RefPtr<dom::Promise> mSeekDOMPromise;
+
+  // Return true if the docshell is inactive and explicitly wants to stop media
+  // playing in that shell.
+  bool ShouldBeSuspendedByInactiveDocShell() const;
+
+  // For debugging bug 1407148.
+  void AssertReadyStateIsNothing();
+
+  // Contains the unique id of the sink device and the device info.
+  // The initial value is ("", nullptr) and the default output device is used.
+  // It can contain an invalid id and info if the device has been
+  // unplugged. It can be set to ("", nullptr). It follows the spec attribute:
+  // https://w3c.github.io/mediacapture-output/#htmlmediaelement-extensions
+  // Read/Write from the main thread only.
+  std::pair<nsString, RefPtr<AudioDeviceInfo>> mSink;
+
+  // This flag is used to control when the user agent is to show a poster frame
+  // for a video element instead of showing the video contents.
+  // https://html.spec.whatwg.org/multipage/media.html#show-poster-flag
+  bool mShowPoster;
+
+  // We may delay starting playback of a media for an unvisited tab until it's
+  // going to foreground. We would create ResumeDelayedMediaPlaybackAgent to
+  // handle related operations at the time whenever delaying media playback is
+  // needed.
+  void CreateResumeDelayedMediaPlaybackAgentIfNeeded();
+  void ClearResumeDelayedMediaPlaybackAgentIfNeeded();
+  RefPtr<ResumeDelayedPlaybackAgent> mResumeDelayedPlaybackAgent;
+  MozPromiseRequestHolder<ResumeDelayedPlaybackAgent::ResumePromise>
+      mResumePlaybackRequest;
+
+  // Return true if we have already a decoder or a src stream and don't have any
+  // error.
+  bool IsPlayable() const;
+
+  // Return true if the media qualifies for being controlled by media control
+  // keys.
+  bool ShouldStartMediaControlKeyListener() const;
+
+  // Start the listener if media fits the requirement of being able to be
+  // controlled be media control keys.
+  void StartMediaControlKeyListenerIfNeeded();
+
+  // It's used to listen media control key, by which we would play or pause
+  // media element.
+  RefPtr<MediaControlKeyListener> mMediaControlKeyListener;
+
+  // Method to update audio stream name
+  void UpdateStreamName();
+
+  // Return true if the media element is being used in picture in picture mode.
+  bool IsBeingUsedInPictureInPictureMode() const;
+
+  // Return true if we should queue a 'timeupdate' event runner to main thread.
+  bool ShouldQueueTimeupdateAsyncTask(TimeupdateType aType) const;
+
+#ifdef MOZ_WMF_CDM
+  // It's used to record telemetry probe for WMFCDM playback.
+  bool mIsUsingWMFCDM = false;
+#endif
+};
+
+// Check if the context is chrome or has the debugger or tabs permission
+bool HasDebuggerOrTabsPrivilege(JSContext* aCx, JSObject* aObj);
+
+}  // namespace mozilla::dom
+
+#endif  // mozilla_dom_HTMLMediaElement_h