Avoid flooding main thread by caching state on media thread.

media/base/pipeline_impl.cc

 // Copyright (c) 2012 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.
 
 #include "media/base/pipeline_impl.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 19 matching lines @@
 #include "media/base/video_decoder_config.h"
 
 static const double kDefaultPlaybackRate = 0.0;
 static const float kDefaultVolume = 1.0f;
 
 namespace media {
 
 class PipelineImpl::RendererWrapper : public DemuxerHost,
                                       public RendererClient {
  public:
-  RendererWrapper(base::WeakPtr<PipelineImpl> weak_pipeline,
-                  scoped_refptr<base::SingleThreadTaskRunner> media_task_runner,
+  RendererWrapper(scoped_refptr<base::SingleThreadTaskRunner> media_task_runner,
                   scoped_refptr<MediaLog> media_log);
   ~RendererWrapper() final;
 
   void Start(Demuxer* demuxer,
              std::unique_ptr<Renderer> renderer,
-             std::unique_ptr<TextRenderer> text_renderer);
+             std::unique_ptr<TextRenderer> text_renderer,
+             base::WeakPtr<PipelineImpl> weak_pipeline);
   void Stop(const base::Closure& stop_cb);
   void Seek(base::TimeDelta time);
   void Suspend();
   void Resume(std::unique_ptr<Renderer> renderer, base::TimeDelta time);
   void SetPlaybackRate(double playback_rate);
   void SetVolume(float volume);
-  base::TimeDelta GetMediaTime();
+  base::TimeDelta GetMediaTime() const;
+  Ranges<base::TimeDelta> GetBufferedTimeRanges() const;
+  bool DidLoadingProgress();
+  PipelineStatistics GetStatistics() const;
   void SetCdm(CdmContext* cdm_context, const CdmAttachedCB& cdm_attached_cb);
 
  private:
+  // Contains state shared between main and media thread.
+  // Main thread can only read. Media thread can both - read and write.
+  // So it is not necessary to lock when reading from the media thread.
+  // This struct should only contain state that is not immediately needed by
+  // PipelineClient and can be cached on the media thread until queried.
+  // Alternatively we could cache it on the main thread by posting the
+  // notification to the main thread. But some of the state change notifications
+  // (OnStatisticsUpdate and OnBufferedTimeRangesChanged) arrive much more
+  // frequently than needed. Posting all those notifications to the main thread
+  // causes performance issues: crbug.com/619975.
+  struct SharedState {
+    // TODO(scherkus): Enforce that Renderer is only called on a single thread,
+    // even for accessing media time http://crbug.com/370634
+    std::unique_ptr<Renderer> renderer;
+
+    // True when OnBufferedTimeRangesChanged() has been called more recently
+    // than DidLoadingProgress().
+    bool did_loading_progress = false;
+
+    // Amount of available buffered data as reported by Demuxer.
+    Ranges<base::TimeDelta> buffered_time_ranges;
+
+    // Accumulated statistics reported by the renderer.
+    PipelineStatistics statistics;
+
+    // The media timestamp to return while the pipeline is suspended.
+    // Otherwise set to kNoTimestamp().
+    base::TimeDelta suspend_timestamp = kNoTimestamp();
+  };
+
   // DemuxerHost implementaion.
   void OnBufferedTimeRangesChanged(const Ranges<base::TimeDelta>& ranges) final;
   void SetDuration(base::TimeDelta duration) final;
   void OnDemuxerError(PipelineStatus error) final;
   void AddTextStream(DemuxerStream* text_stream,
                      const TextTrackConfig& config) final;
   void RemoveTextStream(DemuxerStream* text_stream) final;
 
   // RendererClient implementation.
   void OnError(PipelineStatus error) final;
@@ skipping 13 matching lines @@
   State GetNextState() const;
   void StateTransitionTask(PipelineStatus status);
   void OnCdmAttached(const CdmAttachedCB& cdm_attached_cb,
                      CdmContext* cdm_context,
                      bool success);
   void AddTextStreamTask(DemuxerStream* text_stream,
                          const TextTrackConfig& config);
   void RemoveTextStreamTask(DemuxerStream* text_stream);
   void InitializeDemuxer(const PipelineStatusCB& done_cb);
   void InitializeRenderer(const PipelineStatusCB& done_cb);
+  void DestroyRenderer();
   void ReportMetadata();
 
-  base::WeakPtr<PipelineImpl> weak_pipeline_;
   const scoped_refptr<base::SingleThreadTaskRunner> media_task_runner_;
   const scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
   const scoped_refptr<MediaLog> media_log_;
 
+  base::WeakPtr<PipelineImpl> weak_pipeline_;
   Demuxer* demuxer_;
-  std::unique_ptr<Renderer> renderer_;
   std::unique_ptr<TextRenderer> text_renderer_;
   double playback_rate_;
   float volume_;
   CdmContext* cdm_context_;
 
-  // Lock used to serialize members - |renderer_| and |suspend_timestamp_| -
-  // accessed in GetMediaTime(), which is the only member function called on
-  // the main thread.
-  mutable base::Lock media_time_lock_;
+  // Lock used to serialize |shared_state_|.
+  mutable base::Lock shared_state_lock_;
+
+  // State shared between main and media thread.
+  SharedState shared_state_;
 
   // Current state of the pipeline.
   State state_;
 
   // Status of the pipeline.  Initialized to PIPELINE_OK which indicates that
   // the pipeline is operating correctly. Any other value indicates that the
   // pipeline is stopped or is stopping.  Clients can call the Stop() method to
   // reset the pipeline state, and restore this to PIPELINE_OK.
   PipelineStatus status_;
 
   // The timestamp to start playback from after starting/seeking/resuming has
   // completed.
   base::TimeDelta start_timestamp_;
 
-  // The media timestamp to return while the pipeline is suspended.
-  // Otherwise set to kNoTimestamp().
-  base::TimeDelta suspend_timestamp_;
-
   // Whether we've received the audio/video/text ended events.
   bool renderer_ended_;
   bool text_renderer_ended_;
 
   // Series of tasks to Start(), Seek(), and Resume().
   std::unique_ptr<SerialRunner> pending_callbacks_;
 
   base::WeakPtr<RendererWrapper> weak_this_;
   base::WeakPtrFactory<RendererWrapper> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(RendererWrapper);
 };
 
 PipelineImpl::PipelineImpl(
     const scoped_refptr<base::SingleThreadTaskRunner>& media_task_runner,
     MediaLog* media_log)
     : media_task_runner_(media_task_runner),
       media_log_(media_log),
       client_(nullptr),
       playback_rate_(kDefaultPlaybackRate),
       volume_(kDefaultVolume),
-      did_loading_progress_(false),
       weak_factory_(this) {
   DVLOG(2) << __FUNCTION__;
-  renderer_wrapper_.reset(new RendererWrapper(weak_factory_.GetWeakPtr(),
-                                              media_task_runner_, media_log_));
+  renderer_wrapper_.reset(new RendererWrapper(media_task_runner_, media_log_));
 }
 
 PipelineImpl::~PipelineImpl() {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(!client_) << "Stop() must complete before destroying object";
   DCHECK(seek_cb_.is_null());
   DCHECK(suspend_cb_.is_null());
-
-  // Invalidate self weak pointers effectively canceling all pending
-  // notifications in the message queue.
-  // Do this before posting the DeleteSoon task to the media thread to
-  // guarantee that the WeakPtr<PipelineImpl> passed to the RendererWrapper
-  // is not invalidated on the media thread.
-  weak_factory_.InvalidateWeakPtrs();
+  DCHECK(!weak_factory_.HasWeakPtrs());
 
   // RendererWrapper is deleted on the media thread.
   media_task_runner_->DeleteSoon(FROM_HERE, renderer_wrapper_.release());
 }
 
 void PipelineImpl::Start(Demuxer* demuxer,
                          std::unique_ptr<Renderer> renderer,
                          Client* client,
                          const PipelineStatusCB& seek_cb) {
   DVLOG(2) << __FUNCTION__;
@@ skipping 14 matching lines @@
     text_renderer.reset(new TextRenderer(
         media_task_runner_,
         BindToCurrentLoop(base::Bind(&PipelineImpl::OnAddTextTrack,
                                      weak_factory_.GetWeakPtr()))));
   }
 
   media_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&RendererWrapper::Start,
                  base::Unretained(renderer_wrapper_.get()), demuxer,
-                 base::Passed(&renderer), base::Passed(&text_renderer)));
+                 base::Passed(&renderer), base::Passed(&text_renderer),
+                 weak_factory_.GetWeakPtr()));
 }
 
 void PipelineImpl::Stop() {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (!IsRunning()) {
     DVLOG(2) << "Media pipeline isn't running. Ignoring Stop()";
     return;
   }
 
-  if (statistics_.video_frames_decoded > 0) {
-    UMA_HISTOGRAM_COUNTS("Media.DroppedFrameCount",
-                         statistics_.video_frames_dropped);
-  }
-
   if (media_task_runner_->BelongsToCurrentThread()) {
     // This path is executed by unittests that share media and main threads.
     base::Closure stop_cb = base::Bind(&base::DoNothing);
     media_task_runner_->PostTask(
         FROM_HERE,
         base::Bind(&RendererWrapper::Stop,
                    base::Unretained(renderer_wrapper_.get()), stop_cb));
   } else {
     // This path is executed by production code where the two task runners -
     // main and media - live on different threads.
@@ skipping 16 matching lines @@
         base::Bind(&RendererWrapper::Stop,
                    base::Unretained(renderer_wrapper_.get()), stop_cb)));
     waiter.Wait();
   }
 
   // Once the pipeline is stopped, nothing is reported back to the client.
   // Reset all callbacks and client handle.
   seek_cb_.Reset();
   suspend_cb_.Reset();
   client_ = nullptr;
+
+  // Invalidate self weak pointers effectively canceling all pending
+  // notifications in the message queue.
+  weak_factory_.InvalidateWeakPtrs();
 }
 
 void PipelineImpl::Seek(base::TimeDelta time, const PipelineStatusCB& seek_cb) {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(!seek_cb.is_null());
 
   if (!IsRunning()) {
     DLOG(ERROR) << "Media pipeline isn't running. Ignoring Seek().";
     return;
@@ skipping 80 matching lines @@
                  base::Unretained(renderer_wrapper_.get()), volume_));
 }
 
 base::TimeDelta PipelineImpl::GetMediaTime() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return renderer_wrapper_->GetMediaTime();
 }
 
 Ranges<base::TimeDelta> PipelineImpl::GetBufferedTimeRanges() const {
   DCHECK(thread_checker_.CalledOnValidThread());
-  return buffered_time_ranges_;
+  return renderer_wrapper_->GetBufferedTimeRanges();
 }
 
 base::TimeDelta PipelineImpl::GetMediaDuration() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return duration_;
 }
 
 bool PipelineImpl::DidLoadingProgress() {
   DCHECK(thread_checker_.CalledOnValidThread());
-  bool ret = did_loading_progress_;
-  did_loading_progress_ = false;
-  return ret;
+  return renderer_wrapper_->DidLoadingProgress();
 }
 
 PipelineStatistics PipelineImpl::GetStatistics() const {
   DCHECK(thread_checker_.CalledOnValidThread());
-  return statistics_;
+  return renderer_wrapper_->GetStatistics();
 }
 
 void PipelineImpl::SetCdm(CdmContext* cdm_context,
                           const CdmAttachedCB& cdm_attached_cb) {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(cdm_context);
   DCHECK(!cdm_attached_cb.is_null());
 
   media_task_runner_->PostTask(
@@ skipping 112 matching lines @@
   if (state_ != kPlaying)
     return;
 
   DCHECK(!renderer_ended_);
   renderer_ended_ = true;
   RunEndedCallbackIfNeeded();
 }
 
 void PipelineImpl::RendererWrapper::OnStatisticsUpdate(
     const PipelineStatistics& stats) {
+  DVLOG(3) << __FUNCTION__;
   DCHECK(media_task_runner_->BelongsToCurrentThread());
 
-  main_task_runner_->PostTask(
-      FROM_HERE,
-      base::Bind(&PipelineImpl::OnStatisticsUpdate, weak_pipeline_, stats));
+  base::AutoLock auto_lock(shared_state_lock_);
+  shared_state_.statistics.audio_bytes_decoded += stats.audio_bytes_decoded;
+  shared_state_.statistics.video_bytes_decoded += stats.video_bytes_decoded;
+  shared_state_.statistics.video_frames_decoded += stats.video_frames_decoded;
+  shared_state_.statistics.video_frames_dropped += stats.video_frames_dropped;
+  shared_state_.statistics.audio_memory_usage += stats.audio_memory_usage;
+  shared_state_.statistics.video_memory_usage += stats.video_memory_usage;
 }
 
 void PipelineImpl::RendererWrapper::OnBufferingStateChange(
     BufferingState state) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
   DVLOG(2) << __FUNCTION__ << "(" << state << ") ";
 
   main_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&PipelineImpl::OnBufferingStateChange, weak_pipeline_, state));
@@ skipping 71 matching lines @@
       // meeting 'decode' error when passing media segment but WebMediaPlayer's
       // ready_state_ is still ReadyStateHaveNothing. In that case, it will
       // treat it as NetworkStateFormatError not NetworkStateDecodeError.
       ReportMetadata();
       start_timestamp_ = demuxer_->GetStartTime();
 
       return InitializeRenderer(done_cb);
 
     case kPlaying:
       DCHECK(start_timestamp_ >= base::TimeDelta());
-      renderer_->StartPlayingFrom(start_timestamp_);
+      shared_state_.renderer->StartPlayingFrom(start_timestamp_);
       {
-        base::AutoLock auto_lock(media_time_lock_);
-        suspend_timestamp_ = kNoTimestamp();
+        base::AutoLock auto_lock(shared_state_lock_);
+        shared_state_.suspend_timestamp = kNoTimestamp();
       }
 
       if (text_renderer_)
         text_renderer_->StartPlaying();
 
       main_task_runner_->PostTask(
           FROM_HERE, base::Bind(&PipelineImpl::OnSeekDone, weak_pipeline_,
                                 start_timestamp_));
 
-      renderer_->SetPlaybackRate(playback_rate_);
-      renderer_->SetVolume(volume_);
+      shared_state_.renderer->SetPlaybackRate(playback_rate_);
+      shared_state_.renderer->SetVolume(volume_);
       return;
 
     case kSuspended:
-      renderer_.reset();
+      DestroyRenderer();
+      {
+        base::AutoLock auto_lock(shared_state_lock_);
+        shared_state_.statistics.audio_memory_usage = 0;
+        shared_state_.statistics.video_memory_usage = 0;
+      }
       main_task_runner_->PostTask(
           FROM_HERE, base::Bind(&PipelineImpl::OnSuspendDone, weak_pipeline_,
-                                suspend_timestamp_));
+                                shared_state_.suspend_timestamp));
       return;
 
     case kStopping:
     case kStopped:
     case kCreated:
     case kSeeking:
     case kSuspending:
     case kResuming:
       NOTREACHED() << "State has no transition: " << state_;
       return;
@@ skipping 12 matching lines @@
   DCHECK_EQ(state_, kSeeking);
   SerialRunner::Queue bound_fns;
 
   // Pause.
   if (text_renderer_) {
     bound_fns.Push(base::Bind(&TextRenderer::Pause,
                               base::Unretained(text_renderer_.get())));
   }
 
   // Flush.
-  DCHECK(renderer_);
-  bound_fns.Push(
-      base::Bind(&Renderer::Flush, base::Unretained(renderer_.get())));
+  DCHECK(shared_state_.renderer);
+  bound_fns.Push(base::Bind(&Renderer::Flush,
+                            base::Unretained(shared_state_.renderer.get())));
 
   if (text_renderer_) {
     bound_fns.Push(base::Bind(&TextRenderer::Flush,
                               base::Unretained(text_renderer_.get())));
   }
 
   // Seek demuxer.
   bound_fns.Push(
       base::Bind(&Demuxer::Seek, base::Unretained(demuxer_), seek_timestamp));
 
   pending_callbacks_ = SerialRunner::Run(bound_fns, done_cb);
 }
 
 void PipelineImpl::RendererWrapper::DoStop(const base::Closure& done_cb) {
   DVLOG(2) << __FUNCTION__;
   DCHECK(media_task_runner_->BelongsToCurrentThread());
   DCHECK_EQ(state_, kStopping);
   DCHECK(!pending_callbacks_.get());
 
-  // TODO(scherkus): Enforce that Renderer is only called on a single thread,
-  // even for accessing media time http://crbug.com/370634
-  std::unique_ptr<Renderer> renderer;
-  {
-    base::AutoLock auto_lock(media_time_lock_);
-    renderer.swap(renderer_);
-  }
-  renderer.reset();
+  DestroyRenderer();
   text_renderer_.reset();
 
   if (demuxer_) {
     demuxer_->Stop();
     demuxer_ = NULL;
   }
 
   SetState(kStopped);
 
   // Post the stop callback to enqueue it after the tasks that may have been
   // posted by Demuxer and Renderer during stopping. Note that in theory the
   // tasks posted by Demuxer/Renderer may post even more tasks that will get
   // enqueued after |done_cb|. This may be problematic because Demuxer may
   // get destroyed as soon as |done_cb| is run. In practice this is not a
   // problem, but ideally Demuxer should be destroyed on the media thread.
   media_task_runner_->PostTask(FROM_HERE, done_cb);
 }
 
 void PipelineImpl::RendererWrapper::OnBufferedTimeRangesChanged(
     const Ranges<base::TimeDelta>& ranges) {
   // TODO(alokp): Add thread DCHECK after ensuring that all Demuxer
   // implementations call DemuxerHost on the media thread.
-  main_task_runner_->PostTask(
-      FROM_HERE, base::Bind(&PipelineImpl::OnBufferedTimeRangesChange,
-                            weak_pipeline_, ranges));
+  base::AutoLock auto_lock(shared_state_lock_);
+  shared_state_.did_loading_progress = true;
+  shared_state_.buffered_time_ranges = ranges;
 }
 
 void PipelineImpl::RendererWrapper::Start(
     Demuxer* demuxer,
     std::unique_ptr<Renderer> renderer,
-    std::unique_ptr<TextRenderer> text_renderer) {
+    std::unique_ptr<TextRenderer> text_renderer,
+    base::WeakPtr<PipelineImpl> weak_pipeline) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
   DCHECK_EQ(kCreated, state_) << "Received start in unexpected state: "
                               << state_;
 
   DCHECK(!demuxer_);
-  DCHECK(!renderer_);
+  DCHECK(!shared_state_.renderer);
   DCHECK(!text_renderer_);
   DCHECK(!renderer_ended_);
   DCHECK(!text_renderer_ended_);
+  DCHECK(!weak_pipeline_);
   demuxer_ = demuxer;
   {
-    base::AutoLock auto_lock(media_time_lock_);
-    renderer_ = std::move(renderer);
+    base::AutoLock auto_lock(shared_state_lock_);
+    shared_state_.renderer = std::move(renderer);
   }
   text_renderer_ = std::move(text_renderer);
   if (text_renderer_) {
     text_renderer_->Initialize(
         base::Bind(&RendererWrapper::OnTextRendererEnded, weak_this_));
   }
+  weak_pipeline_ = weak_pipeline;
 
   StateTransitionTask(PIPELINE_OK);
 }
 
 void PipelineImpl::RendererWrapper::Stop(const base::Closure& stop_cb) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
   DCHECK(state_ != kStopping && state_ != kStopped);
 
   SetState(kStopping);
 
+  if (shared_state_.statistics.video_frames_decoded > 0) {
+    UMA_HISTOGRAM_COUNTS("Media.DroppedFrameCount",
+                         shared_state_.statistics.video_frames_dropped);
+  }
+
   // If we stop during starting/seeking/suspending/resuming we don't want to
   // leave outstanding callbacks around. The callbacks also do not get run if
   // the pipeline is stopped before it had a chance to complete outstanding
   // tasks.
   pending_callbacks_.reset();
 
   DoStop(stop_cb);
 }
 
 void PipelineImpl::RendererWrapper::OnPipelineError(PipelineStatus error) {
@@ skipping 18 matching lines @@
   status_ = error;
   main_task_runner_->PostTask(
       FROM_HERE, base::Bind(&PipelineImpl::OnError, weak_pipeline_, error));
 }
 
 void PipelineImpl::RendererWrapper::SetPlaybackRate(double playback_rate) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
 
   playback_rate_ = playback_rate;
   if (state_ == kPlaying)
-    renderer_->SetPlaybackRate(playback_rate_);
+    shared_state_.renderer->SetPlaybackRate(playback_rate_);
 }
 
 void PipelineImpl::RendererWrapper::SetVolume(float volume) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
 
   volume_ = volume;
   if (state_ == kPlaying)
-    renderer_->SetVolume(volume_);
+    shared_state_.renderer->SetVolume(volume_);
 }
 
 void PipelineImpl::RendererWrapper::Seek(base::TimeDelta time) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
 
   // Suppress seeking if we're not fully started.
   if (state_ != kPlaying) {
     DCHECK(state_ == kStopping || state_ == kStopped)
         << "Receive seek in unexpected state: " << state_;
     OnPipelineError(PIPELINE_ERROR_INVALID_STATE);
@@ skipping 15 matching lines @@
 void PipelineImpl::RendererWrapper::Suspend() {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
 
   // Suppress suspending if we're not playing.
   if (state_ != kPlaying) {
     DCHECK(state_ == kStopping || state_ == kStopped)
         << "Receive suspend in unexpected state: " << state_;
     OnPipelineError(PIPELINE_ERROR_INVALID_STATE);
     return;
   }
-  DCHECK(renderer_);
+  DCHECK(shared_state_.renderer);
   DCHECK(!pending_callbacks_.get());
 
   SetState(kSuspending);
 
   // Freeze playback and record the media time before flushing. (Flushing clears
   // the value.)
-  renderer_->SetPlaybackRate(0.0);
+  shared_state_.renderer->SetPlaybackRate(0.0);
   {
-    base::AutoLock auto_lock(media_time_lock_);
-    suspend_timestamp_ = renderer_->GetMediaTime();
-    DCHECK(suspend_timestamp_ != kNoTimestamp());
+    base::AutoLock auto_lock(shared_state_lock_);
+    shared_state_.suspend_timestamp = shared_state_.renderer->GetMediaTime();
+    DCHECK(shared_state_.suspend_timestamp != kNoTimestamp());
   }
 
   // Queue the asynchronous actions required to stop playback. (Matches setup in
   // DoSeek().)
   // TODO(sandersd): Share implementation with DoSeek().
   SerialRunner::Queue fns;
 
   if (text_renderer_) {
     fns.Push(base::Bind(&TextRenderer::Pause,
                         base::Unretained(text_renderer_.get())));
   }
 
-  fns.Push(base::Bind(&Renderer::Flush, base::Unretained(renderer_.get())));
+  fns.Push(base::Bind(&Renderer::Flush,
+                      base::Unretained(shared_state_.renderer.get())));
 
   if (text_renderer_) {
     fns.Push(base::Bind(&TextRenderer::Flush,
                         base::Unretained(text_renderer_.get())));
   }
 
   pending_callbacks_ = SerialRunner::Run(
       fns, base::Bind(&RendererWrapper::StateTransitionTask, weak_this_));
 }
 
 void PipelineImpl::RendererWrapper::Resume(std::unique_ptr<Renderer> renderer,
                                            base::TimeDelta timestamp) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
 
   // Suppress resuming if we're not suspended.
   if (state_ != kSuspended) {
     DCHECK(state_ == kStopping || state_ == kStopped)
         << "Receive resume in unexpected state: " << state_;
     OnPipelineError(PIPELINE_ERROR_INVALID_STATE);
     return;
   }
-  DCHECK(!renderer_);
+  DCHECK(!shared_state_.renderer);
   DCHECK(!pending_callbacks_.get());
 
   SetState(kResuming);
 
   {
-    base::AutoLock auto_lock(media_time_lock_);
-    renderer_ = std::move(renderer);
+    base::AutoLock auto_lock(shared_state_lock_);
+    shared_state_.renderer = std::move(renderer);
   }
 
   // Set up for a seek. (Matches setup in SeekTask().)
   // TODO(sandersd): Share implementation with SeekTask().
   renderer_ended_ = false;
   text_renderer_ended_ = false;
   start_timestamp_ = std::max(timestamp, demuxer_->GetStartTime());
 
   // Queue the asynchronous actions required to start playback. Unlike DoSeek(),
   // we need to initialize the renderer ourselves (we don't want to enter state
   // kInitDemuxer, and even if we did the current code would seek to the start
   // instead of |timestamp|).
   SerialRunner::Queue fns;
 
   fns.Push(
       base::Bind(&Demuxer::Seek, base::Unretained(demuxer_), start_timestamp_));
 
   fns.Push(base::Bind(&RendererWrapper::InitializeRenderer, weak_this_));
 
   pending_callbacks_ = SerialRunner::Run(
       fns, base::Bind(&RendererWrapper::StateTransitionTask, weak_this_));
 }
 
+Ranges<base::TimeDelta> PipelineImpl::RendererWrapper::GetBufferedTimeRanges()
+    const {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+
+  base::AutoLock auto_lock(shared_state_lock_);
+  return shared_state_.buffered_time_ranges;
+}
+
+bool PipelineImpl::RendererWrapper::DidLoadingProgress() {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+
+  base::AutoLock auto_lock(shared_state_lock_);
+  bool did_progress = shared_state_.did_loading_progress;
+  shared_state_.did_loading_progress = false;
+  return did_progress;
+}
+
+PipelineStatistics PipelineImpl::RendererWrapper::GetStatistics() const {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+
+  base::AutoLock auto_lock(shared_state_lock_);
+  return shared_state_.statistics;
+}
+
 void PipelineImpl::RendererWrapper::SetCdm(
     CdmContext* cdm_context,
     const CdmAttachedCB& cdm_attached_cb) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
 
-  if (!renderer_) {
+  if (!shared_state_.renderer) {
     cdm_context_ = cdm_context;
     cdm_attached_cb.Run(true);
     return;
   }
 
-  renderer_->SetCdm(cdm_context,
-                    base::Bind(&RendererWrapper::OnCdmAttached, weak_this_,
-                               cdm_attached_cb, cdm_context));
+  shared_state_.renderer->SetCdm(
+      cdm_context, base::Bind(&RendererWrapper::OnCdmAttached, weak_this_,
+                              cdm_attached_cb, cdm_context));
 }
 
 void PipelineImpl::RendererWrapper::OnCdmAttached(
     const CdmAttachedCB& cdm_attached_cb,
     CdmContext* cdm_context,
     bool success) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
 
   if (success)
     cdm_context_ = cdm_context;
   cdm_attached_cb.Run(success);
 }
 
 void PipelineImpl::RendererWrapper::OnTextRendererEnded() {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
   media_log_->AddEvent(media_log_->CreateEvent(MediaLogEvent::TEXT_ENDED));
 
   if (state_ != kPlaying)
     return;
 
   DCHECK(!text_renderer_ended_);
   text_renderer_ended_ = true;
 
   RunEndedCallbackIfNeeded();
 }
 
 void PipelineImpl::RendererWrapper::RunEndedCallbackIfNeeded() {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
 
-  if (renderer_ && !renderer_ended_)
+  if (shared_state_.renderer && !renderer_ended_)
     return;
 
   if (text_renderer_ && text_renderer_->HasTracks() && !text_renderer_ended_)
     return;
 
   DCHECK_EQ(status_, PIPELINE_OK);
   main_task_runner_->PostTask(
       FROM_HERE, base::Bind(&PipelineImpl::OnEnded, weak_pipeline_));
 }
 
@@ skipping 27 matching lines @@
     const PipelineStatusCB& done_cb) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
 
   if (!demuxer_->GetStream(DemuxerStream::AUDIO) &&
       !demuxer_->GetStream(DemuxerStream::VIDEO)) {
     done_cb.Run(PIPELINE_ERROR_COULD_NOT_RENDER);
     return;
   }
 
   if (cdm_context_)
-    renderer_->SetCdm(cdm_context_, base::Bind(&IgnoreCdmAttached));
+    shared_state_.renderer->SetCdm(cdm_context_,
+                                   base::Bind(&IgnoreCdmAttached));
 
-  renderer_->Initialize(demuxer_, this, done_cb);
+  shared_state_.renderer->Initialize(demuxer_, this, done_cb);
+}
+
+void PipelineImpl::RendererWrapper::DestroyRenderer() {
+  DCHECK(media_task_runner_->BelongsToCurrentThread());
+
+  // Destroy the renderer outside the lock scope to avoid holding the lock
+  // while renderer is being destroyed (in case Renderer destructor is costly).
+  std::unique_ptr<Renderer> renderer;
+  {
+    base::AutoLock auto_lock(shared_state_lock_);
+    renderer.swap(shared_state_.renderer);
+  }
 }
 
 void PipelineImpl::RendererWrapper::ReportMetadata() {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
 
   PipelineMetadata metadata;
   metadata.timeline_offset = demuxer_->GetTimelineOffset();
   DemuxerStream* stream = demuxer_->GetStream(DemuxerStream::VIDEO);
   if (stream) {
     metadata.has_video = true;
     metadata.natural_size = stream->video_decoder_config().natural_size();
     metadata.video_rotation = stream->video_rotation();
   }
   if (demuxer_->GetStream(DemuxerStream::AUDIO)) {
     metadata.has_audio = true;
   }
 
   main_task_runner_->PostTask(FROM_HERE, base::Bind(&PipelineImpl::OnMetadata,
                                                     weak_pipeline_, metadata));
 }
 
 void PipelineImpl::OnError(PipelineStatus error) {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_NE(PIPELINE_OK, error) << "PIPELINE_OK isn't an error!";
-
-  if (!IsRunning())
-    return;
+  DCHECK(IsRunning());
 
   // If the error happens during starting/seeking/suspending/resuming,
   // report the error via the completion callback for those tasks.
   // Else report error via the client interface.
   if (!seek_cb_.is_null()) {
     base::ResetAndReturn(&seek_cb_).Run(error);
   } else if (!suspend_cb_.is_null()) {
     base::ResetAndReturn(&suspend_cb_).Run(error);
   } else {
     DCHECK(client_);
     client_->OnError(error);
   }
 
   // Any kind of error stops the pipeline.
   Stop();
 }
 
 void PipelineImpl::OnEnded() {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(IsRunning());
 
-  if (IsRunning()) {
-    DCHECK(client_);
-    client_->OnEnded();
-  }
+  DCHECK(client_);
+  client_->OnEnded();
 }
 
 void PipelineImpl::OnMetadata(PipelineMetadata metadata) {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(IsRunning());
 
-  if (IsRunning()) {
-    DCHECK(client_);
-    client_->OnMetadata(metadata);
-  }
+  DCHECK(client_);
+  client_->OnMetadata(metadata);
 }
 
 void PipelineImpl::OnBufferingStateChange(BufferingState state) {
   DVLOG(2) << __FUNCTION__ << "(" << state << ")";
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(IsRunning());
 
-  if (IsRunning()) {
-    DCHECK(client_);
-    client_->OnBufferingStateChange(state);
-  }
+  DCHECK(client_);
+  client_->OnBufferingStateChange(state);
 }
 
 void PipelineImpl::OnDurationChange(base::TimeDelta duration) {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(IsRunning());
 
   duration_ = duration;
 
-  if (IsRunning()) {
-    DCHECK(client_);
-    client_->OnDurationChange();
-  }
+  DCHECK(client_);
+  client_->OnDurationChange();
 }
 
 void PipelineImpl::OnAddTextTrack(const TextTrackConfig& config,
                                   const AddTextTrackDoneCB& done_cb) {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(IsRunning());
 
-  if (IsRunning()) {
-    DCHECK(client_);
-    client_->OnAddTextTrack(config, done_cb);
-  }
+  DCHECK(client_);
+  client_->OnAddTextTrack(config, done_cb);
 }
 
 void PipelineImpl::OnWaitingForDecryptionKey() {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(IsRunning());
 
-  if (IsRunning()) {
-    DCHECK(client_);
-    client_->OnWaitingForDecryptionKey();
-  }
+  DCHECK(client_);
+  client_->OnWaitingForDecryptionKey();
 }
 
 void PipelineImpl::OnVideoNaturalSizeChange(const gfx::Size& size) {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(IsRunning());
 
-  if (IsRunning()) {
-    DCHECK(client_);
-    client_->OnVideoNaturalSizeChange(size);
-  }
+  DCHECK(client_);
+  client_->OnVideoNaturalSizeChange(size);
 }
 
 void PipelineImpl::OnVideoOpacityChange(bool opaque) {
   DVLOG(2) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(IsRunning());
 
-  if (IsRunning()) {
-    DCHECK(client_);
-    client_->OnVideoOpacityChange(opaque);
-  }
-}
-
-void PipelineImpl::OnBufferedTimeRangesChange(
-    const Ranges<base::TimeDelta>& ranges) {
-  DVLOG(3) << __FUNCTION__;
-  DCHECK(thread_checker_.CalledOnValidThread());
-
-  buffered_time_ranges_ = ranges;
-  did_loading_progress_ = true;
-}
-
-void PipelineImpl::OnStatisticsUpdate(const PipelineStatistics& stats) {
-  DVLOG(3) << __FUNCTION__;
-  DCHECK(thread_checker_.CalledOnValidThread());
-
-  statistics_.audio_bytes_decoded += stats.audio_bytes_decoded;
-  statistics_.video_bytes_decoded += stats.video_bytes_decoded;
-  statistics_.video_frames_decoded += stats.video_frames_decoded;
-  statistics_.video_frames_dropped += stats.video_frames_dropped;
-  statistics_.audio_memory_usage += stats.audio_memory_usage;
-  statistics_.video_memory_usage += stats.video_memory_usage;
+  DCHECK(client_);
+  client_->OnVideoOpacityChange(opaque);
 }
 
 void PipelineImpl::OnSeekDone(base::TimeDelta start_time) {
   DVLOG(3) << __FUNCTION__ << "(" << start_time.InMicroseconds() << ")";
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(IsRunning());
 
-  if (IsRunning()) {
-    DCHECK(!seek_cb_.is_null());
-    base::ResetAndReturn(&seek_cb_).Run(PIPELINE_OK);
-  }
+  DCHECK(!seek_cb_.is_null());
+  base::ResetAndReturn(&seek_cb_).Run(PIPELINE_OK);
 }
 
 void PipelineImpl::OnSuspendDone(base::TimeDelta suspend_time) {
   DVLOG(3) << __FUNCTION__ << "(" << suspend_time.InMicroseconds() << ")";
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(IsRunning());
 
-  // Reset audio-video memory usage since renderer has been destroyed.
-  statistics_.audio_memory_usage = 0;
-  statistics_.video_memory_usage = 0;
-
-  if (IsRunning()) {
-    DCHECK(!suspend_cb_.is_null());
-    base::ResetAndReturn(&suspend_cb_).Run(PIPELINE_OK);
-  }
+  DCHECK(!suspend_cb_.is_null());
+  base::ResetAndReturn(&suspend_cb_).Run(PIPELINE_OK);
 }
 
 PipelineImpl::RendererWrapper::RendererWrapper(
-    base::WeakPtr<PipelineImpl> weak_pipeline,
     scoped_refptr<base::SingleThreadTaskRunner> media_task_runner,
     scoped_refptr<MediaLog> media_log)
-    : weak_pipeline_(weak_pipeline),
-      media_task_runner_(std::move(media_task_runner)),
+    : media_task_runner_(std::move(media_task_runner)),
       main_task_runner_(base::ThreadTaskRunnerHandle::Get()),
       media_log_(std::move(media_log)),
       demuxer_(nullptr),
       playback_rate_(kDefaultPlaybackRate),
       volume_(kDefaultVolume),
       cdm_context_(nullptr),
       state_(kCreated),
       status_(PIPELINE_OK),
-      suspend_timestamp_(kNoTimestamp()),
       renderer_ended_(false),
       text_renderer_ended_(false),
       weak_factory_(this) {
   weak_this_ = weak_factory_.GetWeakPtr();
   media_log_->AddEvent(media_log_->CreatePipelineStateChangedEvent(kCreated));
 }
 
 PipelineImpl::RendererWrapper::~RendererWrapper() {
   DCHECK(media_task_runner_->BelongsToCurrentThread());
   DCHECK(state_ == kCreated || state_ == kStopped);
 }
 
-base::TimeDelta PipelineImpl::RendererWrapper::GetMediaTime() {
-  // This is the only member function that gets called on the main thread.
-  // TODO(alokp): Enforce that Renderer is only called on a single thread,
-  // even for accessing media time http://crbug.com/370634.
+base::TimeDelta PipelineImpl::RendererWrapper::GetMediaTime() const {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
 
-  base::AutoLock auto_lock(media_time_lock_);
-  if (suspend_timestamp_ != kNoTimestamp())
-    return suspend_timestamp_;
-  return renderer_ ? renderer_->GetMediaTime() : base::TimeDelta();
+  base::AutoLock auto_lock(shared_state_lock_);
+  if (shared_state_.suspend_timestamp != kNoTimestamp())
+    return shared_state_.suspend_timestamp;
+  return shared_state_.renderer ? shared_state_.renderer->GetMediaTime()
+                                : base::TimeDelta();
 }
 
 }  // namespace media