cobalt/dom/media_source.cc

/*
 * Copyright (C) 2013 Google Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// Modifications Copyright 2017 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "cobalt/dom/media_source.h"

#include <algorithm>
#include <cmath>
#include <limits>
#include <vector>

#include "base/compiler_specific.h"
#include "base/guid.h"
#include "base/logging.h"
#include "base/single_thread_task_runner.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/trace_event/trace_event.h"
#include "cobalt/base/polymorphic_downcast.h"
#include "cobalt/base/tokens.h"
#include "cobalt/dom/dom_settings.h"
#include "cobalt/dom/media_settings.h"
#include "cobalt/web/context.h"
#include "cobalt/web/dom_exception.h"
#include "cobalt/web/event.h"
#include "starboard/media.h"
#include "third_party/chromium/media/base/pipeline_status.h"

namespace cobalt {
namespace dom {

namespace {

using ::media::CHUNK_DEMUXER_ERROR_EOS_STATUS_DECODE_ERROR;
using ::media::CHUNK_DEMUXER_ERROR_EOS_STATUS_NETWORK_ERROR;
using ::media::PIPELINE_OK;
using ::media::PipelineStatus;

const MediaSettings& GetMediaSettings(web::EnvironmentSettings* settings) {
  DCHECK(settings);
  DCHECK(settings->context());
  DCHECK(settings->context()->web_settings());

  const auto& web_settings = settings->context()->web_settings();
  return web_settings->media_settings();
}

// If the system has more processors than the specified value, SourceBuffer
// append and remove algorithm will be offloaded to a non-web thread to reduce
// the load on the web thread.
// The default value is 1024, which effectively disable offloading by default.
// Setting to a reasonably low value (say 0 or 2) will enable algorithm
// offloading.
bool IsAlgorithmOffloadEnabled(web::EnvironmentSettings* settings) {
  int min_process_count_to_offload =
      GetMediaSettings(settings)
          .GetMinimumProcessorCountToOffloadAlgorithm()
          .value_or(1024);
  DCHECK_GE(min_process_count_to_offload, 0);
  return SbSystemGetNumberOfProcessors() >= min_process_count_to_offload;
}

// If this function returns true, SourceBuffer will reduce asynchronous
// behaviors.  For example, queued events will be dispatached immediately when
// possible.
// The default value is false.
bool IsAsynchronousReductionEnabled(web::EnvironmentSettings* settings) {
  return GetMediaSettings(settings).IsAsynchronousReductionEnabled().value_or(
      false);
}

// If this function returns true, MediaSource::EndOfStreamAlgorithm() will call
// SetReadyState(kMediaSourceReadyStateEnded) even if MediaSource object is
// closed.
// The default value is false.
bool IsCallingEndedWhenClosedEnabled(web::EnvironmentSettings* settings) {
  return GetMediaSettings(settings).IsCallingEndedWhenClosedEnabled().value_or(
      false);
}

// If the size of a job that is part of an algorithm is less than or equal to
// the return value of this function, the implementation will run the job
// immediately instead of scheduling it to run later to reduce latency.
// NOTE: This is currently only enabled for buffer append.
// The default value is 0 KB, which disables immediate job completely.
int GetMaxSizeForImmediateJob(web::EnvironmentSettings* settings) {
  const int kDefaultMaxSize = 0;
  auto max_size =
      GetMediaSettings(settings).GetMaxSizeForImmediateJob().value_or(
          kDefaultMaxSize);
  DCHECK_GE(max_size, 0);
  return max_size;
}

}  // namespace

MediaSource::MediaSource(script::EnvironmentSettings* settings)
    : web::EventTarget(settings),
      algorithm_offload_enabled_(
          IsAlgorithmOffloadEnabled(environment_settings())),
      asynchronous_reduction_enabled_(
          IsAsynchronousReductionEnabled(environment_settings())),
      max_size_for_immediate_job_(
          GetMaxSizeForImmediateJob(environment_settings())),
      default_algorithm_runner_(asynchronous_reduction_enabled_),
      chunk_demuxer_(NULL),
      ready_state_(kMediaSourceReadyStateClosed),
      ALLOW_THIS_IN_INITIALIZER_LIST(event_queue_(this)),
      source_buffers_(new SourceBufferList(settings, &event_queue_)),
      active_source_buffers_(new SourceBufferList(settings, &event_queue_)),
      live_seekable_range_(new TimeRanges) {
  LOG(INFO) << "Algorithm offloading is "
            << (algorithm_offload_enabled_ ? "enabled" : "disabled");
  LOG(INFO) << "Asynchronous reduction is "
            << (asynchronous_reduction_enabled_ ? "enabled" : "disabled");
  LOG(INFO) << "Max size of immediate job is set to "
            << max_size_for_immediate_job_;
}

MediaSource::~MediaSource() { SetReadyState(kMediaSourceReadyStateClosed); }

scoped_refptr<SourceBufferList> MediaSource::source_buffers() const {
  return source_buffers_;
}

scoped_refptr<SourceBufferList> MediaSource::active_source_buffers() const {
  return active_source_buffers_;
}

MediaSourceReadyState MediaSource::ready_state() const { return ready_state_; }

double MediaSource::duration(script::ExceptionState* exception_state) const {
  if (ready_state_ == kMediaSourceReadyStateClosed) {
    return std::numeric_limits<float>::quiet_NaN();
  }

  DCHECK(chunk_demuxer_);
  return chunk_demuxer_->GetDuration();
}

void MediaSource::set_duration(double duration,
                               script::ExceptionState* exception_state) {
  if (duration < 0.0 || std::isnan(duration)) {
    web::DOMException::Raise(web::DOMException::kIndexSizeErr, exception_state);
    return;
  }
  if (!IsOpen() || IsUpdating()) {
    web::DOMException::Raise(web::DOMException::kInvalidStateErr,
                             exception_state);
    return;
  }

  // Run the duration change algorithm
  if (duration == this->duration(NULL)) {
    return;
  }

  double highest_buffered_presentation_timestamp = 0;
  for (uint32 i = 0; i < source_buffers_->length(); ++i) {
    highest_buffered_presentation_timestamp =
        std::max(highest_buffered_presentation_timestamp,
                 source_buffers_->Item(i)->GetHighestPresentationTimestamp());
  }

  if (duration < highest_buffered_presentation_timestamp) {
    web::DOMException::Raise(web::DOMException::kInvalidStateErr,
                             exception_state);
    return;
  }

  // 3. Set old duration to the current value of duration.
  double old_duration = this->duration(NULL);
  DCHECK_LE(highest_buffered_presentation_timestamp,
            std::isnan(old_duration) ? 0 : old_duration);

  // 4. Update duration to new duration.
  bool request_seek = attached_element_->current_time(NULL) > duration;
  chunk_demuxer_->SetDuration(duration);

  // 5. If a user agent is unable to partially render audio frames or text cues
  //    that start before and end after the duration, then run the following
  //    steps:
  //    NOTE: Currently we assume that the media engine is able to render
  //    partial frames/cues. If a media engine gets added that doesn't support
  //    this, then we'll need to add logic to handle the substeps.

  // 6. Update the media controller duration to new duration and run the
  //    HTMLMediaElement duration change algorithm.
  attached_element_->DurationChanged(duration, request_seek);
}

scoped_refptr<SourceBuffer> MediaSource::AddSourceBuffer(
    script::EnvironmentSettings* settings, const std::string& type,
    script::ExceptionState* exception_state) {
  TRACE_EVENT1("cobalt::dom", "MediaSource::AddSourceBuffer()", "type", type);
  LOG(INFO) << "add SourceBuffer with type " << type;

  if (type.empty()) {
    web::DOMException::Raise(web::DOMException::kInvalidAccessErr,
                             exception_state);
    // Return value should be ignored.
    return NULL;
  }

  if (!IsTypeSupported(settings, type)) {
    web::DOMException::Raise(web::DOMException::kNotSupportedErr,
                             exception_state);
    return NULL;
  }

  if (!IsOpen()) {
    web::DOMException::Raise(web::DOMException::kInvalidStateErr,
                             exception_state);
    return NULL;
  }

  std::string guid = base::GenerateGUID();
  scoped_refptr<SourceBuffer> source_buffer;
  ChunkDemuxer::Status status = chunk_demuxer_->AddId(guid, type);
  switch (status) {
    case ChunkDemuxer::kOk:
      source_buffer =
          new SourceBuffer(settings, guid, this, chunk_demuxer_, &event_queue_);
      break;
    case ChunkDemuxer::kNotSupported:
      web::DOMException::Raise(web::DOMException::kNotSupportedErr,
                               exception_state);
      return NULL;
    case ChunkDemuxer::kReachedIdLimit:
      web::DOMException::Raise(web::DOMException::kQuotaExceededErr,
                               exception_state);
      return NULL;
  }

  DCHECK(source_buffer);
  source_buffers_->Add(source_buffer);
  return source_buffer;
}

void MediaSource::RemoveSourceBuffer(
    const scoped_refptr<SourceBuffer>& source_buffer,
    script::ExceptionState* exception_state) {
  TRACE_EVENT0("cobalt::dom", "MediaSource::RemoveSourceBuffer()");
  if (source_buffer.get() == NULL) {
    web::DOMException::Raise(web::DOMException::kInvalidAccessErr,
                             exception_state);
    return;
  }

  if (source_buffers_->length() == 0 ||
      !source_buffers_->Contains(source_buffer)) {
    web::DOMException::Raise(web::DOMException::kNotFoundErr, exception_state);
    return;
  }

  source_buffer->OnRemovedFromMediaSource();

  active_source_buffers_->Remove(source_buffer);
  source_buffers_->Remove(source_buffer);
}

void MediaSource::EndOfStreamAlgorithm(MediaSourceEndOfStreamError error) {
  if (IsClosed()) {
    if (IsCallingEndedWhenClosedEnabled(environment_settings())) {
      LOG(INFO) << "Setting state to ended when MediaSource object is closed";
      // Calling the function below here leads to ANR in production, as
      // EndOfStreamAlgorithm() can be called by SetReadyState().
      // Calling SetReadyState() nestedly leads to re-entrance of Abort() on
      // the SourceBuffer algorithm handle, where a mutex gets re-acquired.
      // Keep this code path here so we have the option to revert it to the
      // original behavior in production.
      SetReadyState(kMediaSourceReadyStateEnded);
    } else {
      LOG(INFO)
          << "Skip setting state to ended when MediaSource object is closed";
    }
  } else {
    SetReadyState(kMediaSourceReadyStateEnded);
  }

  PipelineStatus pipeline_status = PIPELINE_OK;

  if (error == kMediaSourceEndOfStreamErrorNetwork) {
    pipeline_status = CHUNK_DEMUXER_ERROR_EOS_STATUS_NETWORK_ERROR;
  } else if (error == kMediaSourceEndOfStreamErrorDecode) {
    pipeline_status = CHUNK_DEMUXER_ERROR_EOS_STATUS_DECODE_ERROR;
  }
  chunk_demuxer_->MarkEndOfStream(pipeline_status);
}

void MediaSource::EndOfStream(script::ExceptionState* exception_state) {
  TRACE_EVENT0("cobalt::dom", "MediaSource::EndOfStream()");
  // If there is no error string provided, treat it as empty.
  EndOfStream(kMediaSourceEndOfStreamErrorNoError, exception_state);
}

void MediaSource::EndOfStream(MediaSourceEndOfStreamError error,
                              script::ExceptionState* exception_state) {
  TRACE_EVENT1("cobalt::dom", "MediaSource::EndOfStream()", "error", error);
  if (!IsOpen() || IsUpdating()) {
    web::DOMException::Raise(web::DOMException::kInvalidStateErr,
                             exception_state);
    return;
  }
  EndOfStreamAlgorithm(error);
}

void MediaSource::SetLiveSeekableRange(
    double start, double end, script::ExceptionState* exception_state) {
  TRACE_EVENT2("cobalt::dom", "MediaSource::SetLiveSeekableRange()", "start",
               start, "end", end);
  if (!IsOpen()) {
    web::DOMException::Raise(web::DOMException::kInvalidStateErr,
                             exception_state);
    return;
  }

  if (start < 0 || start > end) {
    web::DOMException::Raise(web::DOMException::kIndexSizeErr, exception_state);
    return;
  }

  live_seekable_range_ = new TimeRanges(start, end);
}

void MediaSource::ClearLiveSeekableRange(
    script::ExceptionState* exception_state) {
  TRACE_EVENT0("cobalt::dom", "MediaSource::ClearLiveSeekableRange()");
  if (!IsOpen()) {
    web::DOMException::Raise(web::DOMException::kInvalidStateErr,
                             exception_state);
    return;
  }

  if (live_seekable_range_->length() != 0) {
    live_seekable_range_ = new TimeRanges;
  }
}

// static
bool MediaSource::IsTypeSupported(script::EnvironmentSettings* settings,
                                  const std::string& type) {
  TRACE_EVENT1("cobalt::dom", "MediaSource::IsTypeSupported()", "type", type);
  DCHECK(settings);
  DOMSettings* dom_settings =
      base::polymorphic_downcast<DOMSettings*>(settings);
  DCHECK(dom_settings->can_play_type_handler());
  SbMediaSupportType support_type =
      dom_settings->can_play_type_handler()->CanPlayAdaptive(type.c_str(), "");
  switch (support_type) {
    case kSbMediaSupportTypeNotSupported:
      return false;
    case kSbMediaSupportTypeMaybe:
      return true;
    case kSbMediaSupportTypeProbably:
      return true;
    default:
      NOTREACHED();
      return false;
  }
}

bool MediaSource::AttachToElement(HTMLMediaElement* media_element) {
  if (attached_element_) {
    return false;
  }

  DCHECK(IsClosed());
  DCHECK(!algorithm_process_thread_);

  attached_element_ = base::AsWeakPtr(media_element);
  has_max_video_capabilities_ = media_element->HasMaxVideoCapabilities();

  if (algorithm_offload_enabled_) {
    algorithm_process_thread_.reset(new base::Thread("MSEAlgorithm"));
    if (!algorithm_process_thread_->Start()) {
      LOG(WARNING) << "Starting algorithm process thread failed, disable"
                      " algorithm offloading";
      algorithm_process_thread_.reset();
    }
  }

  if (algorithm_process_thread_) {
    LOG(INFO) << "Algorithm offloading enabled.";
    offload_algorithm_runner_.reset(
        new OffloadAlgorithmRunner<SourceBufferAlgorithm>(
            algorithm_process_thread_->message_loop()->task_runner(),
            base::ThreadTaskRunnerHandle::Get()));
  } else {
    LOG(INFO) << "Algorithm offloading disabled.";
  }
  return true;
}

void MediaSource::SetChunkDemuxerAndOpen(ChunkDemuxer* chunk_demuxer) {
  DCHECK(chunk_demuxer);
  DCHECK(!chunk_demuxer_);
  DCHECK(attached_element_);
  chunk_demuxer_ = chunk_demuxer;
  SetReadyState(kMediaSourceReadyStateOpen);
}

void MediaSource::Close() { SetReadyState(kMediaSourceReadyStateClosed); }

bool MediaSource::IsClosed() const {
  return ready_state_ == kMediaSourceReadyStateClosed;
}

scoped_refptr<TimeRanges> MediaSource::GetBufferedRange() const {
  std::vector<scoped_refptr<TimeRanges> > ranges(
      active_source_buffers_->length());
  for (uint32 i = 0; i < active_source_buffers_->length(); ++i)
    ranges[i] = active_source_buffers_->Item(i)->buffered(NULL);

  if (ranges.empty()) {
    return new TimeRanges;
  }

  double highest_end_time = -1;
  for (size_t i = 0; i < ranges.size(); ++i) {
    uint32 length = ranges[i]->length();
    if (length > 0) {
      highest_end_time =
          std::max(highest_end_time, ranges[i]->End(length - 1, NULL));
    }
  }

  // Return an empty range if all ranges are empty.
  if (highest_end_time < 0) {
    return new TimeRanges;
  }

  scoped_refptr<TimeRanges> intersection_ranges =
      new TimeRanges(0, highest_end_time);

  bool ended = ready_state() == kMediaSourceReadyStateEnded;
  for (size_t i = 0; i < ranges.size(); ++i) {
    scoped_refptr<TimeRanges> source_ranges = ranges[i].get();

    if (ended && source_ranges->length()) {
      source_ranges->Add(
          source_ranges->Start(source_ranges->length() - 1, NULL),
          highest_end_time);
    }

    intersection_ranges = intersection_ranges->IntersectWith(source_ranges);
  }

  return intersection_ranges;
}

scoped_refptr<TimeRanges> MediaSource::GetSeekable() const {
  // Implements MediaSource algorithm for HTMLMediaElement.seekable.
  double source_duration = duration(NULL);

  if (std::isnan(source_duration)) {
    return new TimeRanges;
  }

  if (source_duration == std::numeric_limits<double>::infinity()) {
    scoped_refptr<TimeRanges> buffered = attached_element_->buffered();

    if (live_seekable_range_->length() != 0) {
      if (buffered->length() == 0) {
        return new TimeRanges(live_seekable_range_->Start(0, NULL),
                              live_seekable_range_->End(0, NULL));
      }

      return new TimeRanges(
          std::min(live_seekable_range_->Start(0, NULL),
                   buffered->Start(0, NULL)),
          std::max(live_seekable_range_->End(0, NULL),
                   buffered->End(buffered->length() - 1, NULL)));
    }

    if (buffered->length() == 0) {
      return new TimeRanges;
    }

    return new TimeRanges(0, buffered->End(buffered->length() - 1, NULL));
  }

  return new TimeRanges(0, source_duration);
}

void MediaSource::OnAudioTrackChanged(AudioTrack* audio_track) {
  scoped_refptr<SourceBuffer> source_buffer = audio_track->source_buffer();

  if (!source_buffer) {
    return;
  }

  DCHECK(source_buffers_->Contains(source_buffer));
  source_buffer->audio_tracks()->ScheduleChangeEvent();

  bool is_active = (source_buffer->video_tracks()->selected_index() != -1) ||
                   source_buffer->audio_tracks()->HasEnabledTrack();
  SetSourceBufferActive(source_buffer, is_active);
}

void MediaSource::OnVideoTrackChanged(VideoTrack* video_track) {
  scoped_refptr<SourceBuffer> source_buffer = video_track->source_buffer();

  if (!source_buffer) {
    return;
  }

  DCHECK(source_buffers_->Contains(source_buffer));
  if (video_track->selected()) {
    source_buffer->video_tracks()->OnTrackSelected(video_track->id());
  }
  source_buffer->video_tracks()->ScheduleChangeEvent();

  bool is_active = source_buffer->video_tracks()->selected_index() != -1 ||
                   source_buffer->audio_tracks()->HasEnabledTrack();

  SetSourceBufferActive(source_buffer, is_active);
}

void MediaSource::OpenIfInEndedState() {
  if (ready_state_ != kMediaSourceReadyStateEnded) {
    return;
  }

  SetReadyState(kMediaSourceReadyStateOpen);
  chunk_demuxer_->UnmarkEndOfStream();
}

bool MediaSource::IsOpen() const {
  return ready_state_ == kMediaSourceReadyStateOpen;
}

void MediaSource::SetSourceBufferActive(SourceBuffer* source_buffer,
                                        bool is_active) {
  // We don't support deactivate a source buffer.
  DCHECK(is_active);
  DCHECK(source_buffers_->Contains(source_buffer));

  if (!is_active) {
    DCHECK(active_source_buffers_->Contains(source_buffer));
    active_source_buffers_->Remove(source_buffer);
    return;
  }

  if (active_source_buffers_->Contains(source_buffer)) {
    return;
  }

  size_t index = source_buffers_->Find(source_buffer);

  uint32 insert_position = 0;
  while (insert_position < active_source_buffers_->length() &&
         source_buffers_->Find(active_source_buffers_->Item(insert_position)) <
             index) {
    ++insert_position;
  }

  active_source_buffers_->Insert(insert_position, source_buffer);
}

HTMLMediaElement* MediaSource::GetMediaElement() const {
  return attached_element_;
}

bool MediaSource::MediaElementHasMaxVideoCapabilities() const {
  SB_DCHECK(attached_element_);
  return has_max_video_capabilities_;
}

SerializedAlgorithmRunner<SourceBufferAlgorithm>*
MediaSource::GetAlgorithmRunner(int job_size) {
  if (!asynchronous_reduction_enabled_ &&
      job_size <= max_size_for_immediate_job_) {
    // `default_algorithm_runner_` won't run jobs immediately when
    // `asynchronous_reduction_enabled_` is false, so we use
    // `immediate_job_algorithm_runner_` instead, which always has asynchronous
    // reduction enabled.
    return &immediate_job_algorithm_runner_;
  }
  if (!offload_algorithm_runner_) {
    return &default_algorithm_runner_;
  }
  // The logic below is redundant as the code for immediate job can be
  // consolidated with value of `asynchronous_reduction_enabled_` ignored.  It's
  // kept as is to leave existing behavior unchanged.
  if (asynchronous_reduction_enabled_ &&
      job_size <= max_size_for_immediate_job_) {
    // Append without posting new tasks is only supported on the default runner.
    return &default_algorithm_runner_;
  }
  return offload_algorithm_runner_.get();
}

void MediaSource::TraceMembers(script::Tracer* tracer) {
  web::EventTarget::TraceMembers(tracer);

  tracer->Trace(event_queue_);
  tracer->Trace(attached_element_);
  tracer->Trace(source_buffers_);
  tracer->Trace(active_source_buffers_);
  tracer->Trace(live_seekable_range_);
}

void MediaSource::SetReadyState(MediaSourceReadyState ready_state) {
  if (!offload_algorithm_runner_) {
    // Setting `chunk_demuxer_` to NULL when there is an active algorithm
    // running may cause crash.  So `chunk_demuxer_` is reset later in the
    // function.
    // When `offload_algorithm_runner_` is null, the logic is kept as is to
    // ensure that the behavior stays the same when offload is not enabled.
    if (ready_state == kMediaSourceReadyStateClosed) {
      chunk_demuxer_ = NULL;
    }
  }

  if (ready_state_ == ready_state) {
    return;
  }

  MediaSourceReadyState old_state = ready_state_;
  ready_state_ = ready_state;

  if (IsOpen()) {
    ScheduleEvent(base::Tokens::sourceopen());
    return;
  }

  if (old_state == kMediaSourceReadyStateOpen &&
      ready_state_ == kMediaSourceReadyStateEnded) {
    ScheduleEvent(base::Tokens::sourceended());
    return;
  }

  DCHECK(IsClosed());

  active_source_buffers_->Clear();

  // Clear SourceBuffer references to this object.
  for (uint32 i = 0; i < source_buffers_->length(); ++i) {
    source_buffers_->Item(i)->OnRemovedFromMediaSource();
  }
  source_buffers_->Clear();

  attached_element_.reset();

  ScheduleEvent(base::Tokens::sourceclose());

  if (algorithm_process_thread_) {
    algorithm_process_thread_->Stop();
    algorithm_process_thread_.reset();
  }
  offload_algorithm_runner_.reset();
  chunk_demuxer_ = NULL;
}

bool MediaSource::IsUpdating() const {
  // Return true if any member of |source_buffers_| is updating.
  for (uint32 i = 0; i < source_buffers_->length(); ++i) {
    if (source_buffers_->Item(i)->updating()) {
      return true;
    }
  }

  return false;
}

void MediaSource::ScheduleEvent(base::Token event_name) {
  scoped_refptr<web::Event> event = new web::Event(event_name);
  event->set_target(this);
  event_queue_.Enqueue(event);
}

}  // namespace dom
}  // namespace cobalt