chromium/src/third_party/blink/renderer/modules/mediasource/same_thread_media_source_attachment.h

// Copyright 2020 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_MEDIASOURCE_SAME_THREAD_MEDIA_SOURCE_ATTACHMENT_H_
#define THIRD_PARTY_BLINK_RENDERER_MODULES_MEDIASOURCE_SAME_THREAD_MEDIA_SOURCE_ATTACHMENT_H_

#include <memory>

#include "base/types/pass_key.h"
#include "third_party/blink/public/platform/web_time_range.h"
#include "third_party/blink/renderer/core/html/track/audio_track.h"
#include "third_party/blink/renderer/core/html/track/audio_track_list.h"
#include "third_party/blink/renderer/core/html/track/video_track.h"
#include "third_party/blink/renderer/core/html/track/video_track_list.h"
#include "third_party/blink/renderer/modules/mediasource/media_source.h"
#include "third_party/blink/renderer/modules/mediasource/media_source_attachment_supplement.h"
#include "third_party/blink/renderer/modules/mediasource/url_media_source.h"
#include "third_party/blink/renderer/platform/heap/persistent.h"

namespace blink {

// Concrete attachment that supports operation only on the main thread.
class SameThreadMediaSourceAttachment final
    : public MediaSourceAttachmentSupplement {
 public:
  // The only intended caller of this constructor is
  // URLMediaSource::createObjectUrl, made more clear by using the PassKey. The
  // raw pointer is then adopted into a scoped_refptr in
  // MediaSourceRegistryImpl::RegisterURL.
  SameThreadMediaSourceAttachment(MediaSource* media_source,
                                  base::PassKey<URLMediaSource>);

  // MediaSourceAttachmentSupplement
  void NotifyDurationChanged(MediaSourceTracer* tracer, double duration) final;
  double GetRecentMediaTime(MediaSourceTracer* tracer) final;
  bool GetElementError(MediaSourceTracer* tracer) final;
  AudioTrackList* CreateAudioTrackList(MediaSourceTracer* tracer) final;
  VideoTrackList* CreateVideoTrackList(MediaSourceTracer* tracer) final;
  void AddAudioTrackToMediaElement(MediaSourceTracer* tracer,
                                   AudioTrack* track) final;
  void AddVideoTrackToMediaElement(MediaSourceTracer* tracer,
                                   VideoTrack* track) final;
  void RemoveAudioTracksFromMediaElement(MediaSourceTracer* tracer,
                                         Vector<String> audio_ids,
                                         bool enqueue_change_event) final;
  void RemoveVideoTracksFromMediaElement(MediaSourceTracer* tracer,
                                         Vector<String> video_ids,
                                         bool enqueue_change_event) final;
  void OnMediaSourceContextDestroyed() final;

  // MediaSourceAttachment
  void Unregister() final;
  MediaSourceTracer* StartAttachingToMediaElement(HTMLMediaElement*,
                                                  bool* success) final;
  void CompleteAttachingToMediaElement(MediaSourceTracer* tracer,
                                       std::unique_ptr<WebMediaSource>) final;

  void Close(MediaSourceTracer* tracer) final;
  WebTimeRanges BufferedInternal(MediaSourceTracer* tracer) const final;
  WebTimeRanges SeekableInternal(MediaSourceTracer* tracer) const final;
  void OnTrackChanged(MediaSourceTracer* tracer, TrackBase*) final;

  void OnElementTimeUpdate(double time) final;
  void OnElementError() final;
  void OnElementContextDestroyed() final;

 private:
  ~SameThreadMediaSourceAttachment() override;

  // In this same thread implementation, if the media element context is
  // destroyed, then so should be the Media Source's context. This method
  // this precondition in debug mode.
  void VerifyCalledWhileContextsAliveForDebugging() const;

  // Cache of the registered MediaSource. Retains strong reference from
  // construction of this object until Unregister() is called.
  Persistent<MediaSource> registered_media_source_;

  // These are mostly used to verify correct behavior of the media element and
  // media source state pumping in debug builds. In a cross-thread attachment
  // implementation, state like this will be relied upon for servicing the
  // MediaSource API.
  double recent_element_time_;           // See OnElementTimeUpdate().
  bool element_has_error_;               // See OnElementError().
  bool element_context_destroyed_;       // See OnElementContextDestroyed().
  bool media_source_context_destroyed_;  // See OnMediaSourceContextDestroyed().

  DISALLOW_COPY_AND_ASSIGN(SameThreadMediaSourceAttachment);
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_MODULES_MEDIASOURCE_SAME_THREAD_MEDIA_SOURCE_ATTACHMENT_H_