Refactor VideoRendererImpl to use VideoFrameScheduler.

media/filters/video_renderer_impl.cc

Index: media/filters/video_renderer_impl.cc
diff --git a/media/filters/video_renderer_impl.cc b/media/filters/video_renderer_impl.cc
index 7d99dbf14a4bbfda6a7b5c68b8e253ddb46dd4f8..a3589accfc796205eca59d4a20cade9c000c240c 100644
--- a/media/filters/video_renderer_impl.cc
+++ b/media/filters/video_renderer_impl.cc
@@ -5,74 +5,73 @@
 #include "media/filters/video_renderer_impl.h"
 
 #include "base/bind.h"
-#include "base/callback.h"
 #include "base/callback_helpers.h"
-#include "base/debug/trace_event.h"
-#include "base/location.h"
 #include "base/single_thread_task_runner.h"
-#include "base/threading/platform_thread.h"
-#include "media/base/buffers.h"
+#include "base/time/default_tick_clock.h"
 #include "media/base/limits.h"
-#include "media/base/pipeline.h"
 #include "media/base/video_frame.h"
 
 namespace media {
 
 VideoRendererImpl::VideoRendererImpl(
     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
+    scoped_ptr<VideoFrameScheduler> scheduler,
     ScopedVector<VideoDecoder> decoders,
-    const SetDecryptorReadyCB& set_decryptor_ready_cb,
-    const PaintCB& paint_cb,
-    bool drop_frames)
+    const SetDecryptorReadyCB& set_decryptor_ready_cb)
     : task_runner_(task_runner),
+      scheduler_(scheduler.Pass()),
+      tick_clock_(new base::DefaultTickClock()),
       video_frame_stream_(task_runner, decoders.Pass(), set_decryptor_ready_cb),
+      next_scheduled_frame_id_(0),
       received_end_of_stream_(false),
-      frame_available_(&lock_),
       state_(kUninitialized),
-      thread_(),
       pending_read_(false),
-      drop_frames_(drop_frames),
       playback_rate_(0),
-      paint_cb_(paint_cb),
-      last_timestamp_(kNoTimestamp()),
       frames_decoded_(0),
       frames_dropped_(0),
       weak_factory_(this) {
-  DCHECK(!paint_cb_.is_null());
 }
 
 VideoRendererImpl::~VideoRendererImpl() {
-  base::AutoLock auto_lock(lock_);
   CHECK(state_ == kStopped || state_ == kUninitialized) << state_;
-  CHECK(thread_.is_null());
 }
 
 void VideoRendererImpl::Play(const base::Closure& callback) {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  base::AutoLock auto_lock(lock_);
   DCHECK_EQ(kPrerolled, state_);
   state_ = kPlaying;
+
+  ScheduleAllFrames();
+  AttemptRead();
+
+  // Changing from non-playing to playing state can trigger ended.
+  if (ShouldTransitionToEnded())
+    TransitionToEnded();
+
   callback.Run();
 }
 
 void VideoRendererImpl::Pause(const base::Closure& callback) {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  base::AutoLock auto_lock(lock_);
   DCHECK(state_ != kUninitialized || state_ == kError);
+
   state_ = kPaused;
+  ResetScheduler();
+
   callback.Run();
 }
 
 void VideoRendererImpl::Flush(const base::Closure& callback) {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  base::AutoLock auto_lock(lock_);
   DCHECK_EQ(state_, kPaused);
+  DCHECK_EQ(scheduled_frames_.size(), 0u);
   flush_cb_ = callback;
   state_ = kFlushing;
 
   // This is necessary if the |video_frame_stream_| has already seen an end of
   // stream and needs to drain it before flushing it.
-  ready_frames_.clear();
+  unscheduled_frames_.clear();
+
   received_end_of_stream_ = false;
   video_frame_stream_.Reset(
       base::Bind(&VideoRendererImpl::OnVideoFrameStreamResetDone,
@@ -81,7 +80,6 @@ void VideoRendererImpl::Flush(const base::Closure& callback) {
 
 void VideoRendererImpl::Stop(const base::Closure& callback) {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  base::AutoLock auto_lock(lock_);
   if (state_ == kUninitialized || state_ == kStopped) {
     callback.Run();
     return;
@@ -94,44 +92,40 @@ void VideoRendererImpl::Stop(const base::Closure& callback) {
 
   statistics_cb_.Reset();
   max_time_cb_.Reset();
-  DoStopOrError_Locked();
-
-  // Clean up our thread if present.
-  base::PlatformThreadHandle thread_to_join = base::PlatformThreadHandle();
-  if (!thread_.is_null()) {
-    // Signal the thread since it's possible to get stopped with the video
-    // thread waiting for a read to complete.
-    frame_available_.Signal();
-    std::swap(thread_, thread_to_join);
-  }
 
-  if (!thread_to_join.is_null()) {
-    base::AutoUnlock auto_unlock(lock_);
-    base::PlatformThread::Join(thread_to_join);
-  }
+  unscheduled_frames_.clear();
+  scheduled_frames_.clear();
+  scheduler_->Reset();
 
   video_frame_stream_.Stop(callback);
 }
 
 void VideoRendererImpl::SetPlaybackRate(float playback_rate) {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  base::AutoLock auto_lock(lock_);
+  if (playback_rate_ == playback_rate)
+    return;
+
   playback_rate_ = playback_rate;
+  ResetScheduler();
+
+  if (state_ == kPlaying)
+    ScheduleAllFrames();
 }
 
 void VideoRendererImpl::Preroll(base::TimeDelta time,
                                 const PipelineStatusCB& cb) {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  base::AutoLock auto_lock(lock_);
   DCHECK(!cb.is_null());
   DCHECK(preroll_cb_.is_null());
-  DCHECK(state_ == kFlushed || state_== kPaused) << "state_ " << state_;
+  DCHECK(state_ == kFlushed || state_ == kPaused) << "state_ " << state_;
 
   if (state_ == kFlushed) {
     DCHECK(time != kNoTimestamp());
     DCHECK(!pending_read_);
-    DCHECK(ready_frames_.empty());
+    DCHECK(unscheduled_frames_.empty());
+    DCHECK(scheduled_frames_.empty());
   } else {
+    // Prerolling without a timestamp is used for rebuffering.
     DCHECK(time == kNoTimestamp());
   }
 
@@ -139,12 +133,12 @@ void VideoRendererImpl::Preroll(base::TimeDelta time,
   preroll_cb_ = cb;
   preroll_timestamp_ = time;
 
-  if (ShouldTransitionToPrerolled_Locked()) {
-    TransitionToPrerolled_Locked();
+  if (ShouldTransitionToPrerolled()) {
+    TransitionToPrerolled();
     return;
   }
 
-  AttemptRead_Locked();
+  AttemptRead();
 }
 
 void VideoRendererImpl::Initialize(DemuxerStream* stream,
@@ -156,7 +150,6 @@ void VideoRendererImpl::Initialize(DemuxerStream* stream,
                                    const TimeDeltaCB& get_time_cb,
                                    const TimeDeltaCB& get_duration_cb) {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  base::AutoLock auto_lock(lock_);
   DCHECK(stream);
   DCHECK_EQ(stream->type(), DemuxerStream::VIDEO);
   DCHECK(!init_cb.is_null());
@@ -185,7 +178,6 @@ void VideoRendererImpl::Initialize(DemuxerStream* stream,
 
 void VideoRendererImpl::OnVideoFrameStreamInitialized(bool success) {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  base::AutoLock auto_lock(lock_);
 
   if (state_ == kStopped)
     return;
@@ -198,143 +190,14 @@ void VideoRendererImpl::OnVideoFrameStreamInitialized(bool success) {
     return;
   }
 
-  // We're all good!  Consider ourselves flushed. (ThreadMain() should never
-  // see us in the kUninitialized state).
-  // Since we had an initial Preroll(), we consider ourself flushed, because we
-  // have not populated any buffers yet.
+  // Consider ourselves flushed as no frames have been received yet.
   state_ = kFlushed;
 
-  // Create our video thread.
-  if (!base::PlatformThread::Create(0, this, &thread_)) {
-    NOTREACHED() << "Video thread creation failed";
-    state_ = kError;
-    base::ResetAndReturn(&init_cb_).Run(PIPELINE_ERROR_INITIALIZATION_FAILED);
-    return;
-  }
-
-#if defined(OS_WIN)
-  // Bump up our priority so our sleeping is more accurate.
-  // TODO(scherkus): find out if this is necessary, but it seems to help.
-  ::SetThreadPriority(thread_.platform_handle(), THREAD_PRIORITY_ABOVE_NORMAL);
-#endif  // defined(OS_WIN)
   base::ResetAndReturn(&init_cb_).Run(PIPELINE_OK);
 }
 
-// PlatformThread::Delegate implementation.
-void VideoRendererImpl::ThreadMain() {
-  base::PlatformThread::SetName("CrVideoRenderer");
-
-  // The number of milliseconds to idle when we do not have anything to do.
-  // Nothing special about the value, other than we're being more OS-friendly
-  // than sleeping for 1 millisecond.
-  //
-  // TODO(scherkus): switch to pure event-driven frame timing instead of this
-  // kIdleTimeDelta business http://crbug.com/106874
-  const base::TimeDelta kIdleTimeDelta =
-      base::TimeDelta::FromMilliseconds(10);
-
-  for (;;) {
-    base::AutoLock auto_lock(lock_);
-
-    // Thread exit condition.
-    if (state_ == kStopped)
-      return;
-
-    // Remain idle as long as we're not playing.
-    if (state_ != kPlaying || playback_rate_ == 0) {
-      UpdateStatsAndWait_Locked(kIdleTimeDelta);
-      continue;
-    }
-
-    // Remain idle until we have the next frame ready for rendering.
-    if (ready_frames_.empty()) {
-      if (received_end_of_stream_) {
-        state_ = kEnded;
-        ended_cb_.Run();
-
-        // No need to sleep here as we idle when |state_ != kPlaying|.
-        continue;
-      }
-
-      UpdateStatsAndWait_Locked(kIdleTimeDelta);
-      continue;
-    }
-
-    base::TimeDelta remaining_time =
-        CalculateSleepDuration(ready_frames_.front(), playback_rate_);
-
-    // Sleep up to a maximum of our idle time until we're within the time to
-    // render the next frame.
-    if (remaining_time.InMicroseconds() > 0) {
-      remaining_time = std::min(remaining_time, kIdleTimeDelta);
-      UpdateStatsAndWait_Locked(remaining_time);
-      continue;
-    }
-
-    // Deadline is defined as the midpoint between this frame and the next
-    // frame, using the delta between this frame and the previous frame as the
-    // assumption for frame duration.
-    //
-    // TODO(scherkus): An improvement over midpoint might be selecting the
-    // minimum and/or maximum between the midpoint and some constants. As a
-    // thought experiment, consider what would be better than the midpoint
-    // for both the 1fps case and 120fps case.
-    //
-    // TODO(scherkus): This can be vastly improved. Use a histogram to measure
-    // the accuracy of our frame timing code. http://crbug.com/149829
-    if (drop_frames_ && last_timestamp_ != kNoTimestamp()) {
-      base::TimeDelta now = get_time_cb_.Run();
-      base::TimeDelta deadline = ready_frames_.front()->timestamp() +
-          (ready_frames_.front()->timestamp() - last_timestamp_) / 2;
-
-      if (now > deadline) {
-        DropNextReadyFrame_Locked();
-        continue;
-      }
-    }
-
-    // Congratulations! You've made it past the video frame timing gauntlet.
-    //
-    // At this point enough time has passed that the next frame that ready for
-    // rendering.
-    PaintNextReadyFrame_Locked();
-  }
-}
-
-void VideoRendererImpl::PaintNextReadyFrame_Locked() {
-  lock_.AssertAcquired();
-
-  scoped_refptr<VideoFrame> next_frame = ready_frames_.front();
-  ready_frames_.pop_front();
-  frames_decoded_++;
-
-  last_timestamp_ = next_frame->timestamp();
-
-  paint_cb_.Run(next_frame);
-
-  task_runner_->PostTask(
-      FROM_HERE,
-      base::Bind(&VideoRendererImpl::AttemptRead, weak_factory_.GetWeakPtr()));
-}
-
-void VideoRendererImpl::DropNextReadyFrame_Locked() {
-  TRACE_EVENT0("media", "VideoRendererImpl:frameDropped");
-
-  lock_.AssertAcquired();
-
-  last_timestamp_ = ready_frames_.front()->timestamp();
-  ready_frames_.pop_front();
-  frames_decoded_++;
-  frames_dropped_++;
-
-  task_runner_->PostTask(
-      FROM_HERE,
-      base::Bind(&VideoRendererImpl::AttemptRead, weak_factory_.GetWeakPtr()));
-}
-
 void VideoRendererImpl::FrameReady(VideoFrameStream::Status status,
                                    const scoped_refptr<VideoFrame>& frame) {
-  base::AutoLock auto_lock(lock_);
   DCHECK_NE(state_, kUninitialized);
   DCHECK_NE(state_, kFlushed);
 
@@ -367,7 +230,7 @@ void VideoRendererImpl::FrameReady(VideoFrameStream::Status status,
     // A new preroll will be requested after this one completes so there is no
     // point trying to collect more frames.
     if (state_ == kPrerolling)
-      TransitionToPrerolled_Locked();
+      TransitionToPrerolled();
 
     return;
   }
@@ -378,7 +241,10 @@ void VideoRendererImpl::FrameReady(VideoFrameStream::Status status,
     max_time_cb_.Run(get_duration_cb_.Run());
 
     if (state_ == kPrerolling)
-      TransitionToPrerolled_Locked();
+      TransitionToPrerolled();
+
+    if (ShouldTransitionToEnded())
+      TransitionToEnded();
 
     return;
   }
@@ -387,32 +253,9 @@ void VideoRendererImpl::FrameReady(VideoFrameStream::Status status,
   // prerolling has completed.
   if (state_ == kPrerolling && preroll_timestamp_ != kNoTimestamp() &&
       frame->timestamp() <= preroll_timestamp_) {
-    ready_frames_.clear();
+    unscheduled_frames_.clear();
   }
 
-  AddReadyFrame_Locked(frame);
-
-  if (ShouldTransitionToPrerolled_Locked())
-    TransitionToPrerolled_Locked();
-
-  // Always request more decoded video if we have capacity. This serves two
-  // purposes:
-  //   1) Prerolling while paused
-  //   2) Keeps decoding going if video rendering thread starts falling behind
-  AttemptRead_Locked();
-}
-
-bool VideoRendererImpl::ShouldTransitionToPrerolled_Locked() {
-  return state_ == kPrerolling &&
-      (!video_frame_stream_.CanReadWithoutStalling() ||
-       ready_frames_.size() >= static_cast<size_t>(limits::kMaxVideoFrames));
-}
-
-void VideoRendererImpl::AddReadyFrame_Locked(
-    const scoped_refptr<VideoFrame>& frame) {
-  lock_.AssertAcquired();
-  DCHECK(!frame->end_of_stream());
-
   // Adjust the incoming frame if its rendering stop time is past the duration
   // of the video itself. This is typically the last frame of the video and
   // occurs if the container specifies a duration that isn't a multiple of the
@@ -423,28 +266,49 @@ void VideoRendererImpl::AddReadyFrame_Locked(
     frame->set_timestamp(duration);
   }
 
-  ready_frames_.push_back(frame);
-  DCHECK_LE(ready_frames_.size(),
-            static_cast<size_t>(limits::kMaxVideoFrames));
+  unscheduled_frames_.push_back(frame);
+  DCHECK_LE(video_frame_count(), limits::kMaxVideoFrames);
 
   max_time_cb_.Run(frame->timestamp());
 
-  // Avoid needlessly waking up |thread_| unless playing.
+  if (ShouldTransitionToPrerolled())
+    TransitionToPrerolled();
+
   if (state_ == kPlaying)
-    frame_available_.Signal();
+    ScheduleAllFrames();
+
+  if (ShouldTransitionToEnded())
+    TransitionToEnded();
+
+  // Always request more decoded video if we have capacity. This serves two
+  // purposes:
+  //   1) Prerolling while paused
+  //   2) Keeps decoding going if video rendering thread starts falling behind
+  AttemptRead();
 }
 
-void VideoRendererImpl::AttemptRead() {
-  base::AutoLock auto_lock(lock_);
-  AttemptRead_Locked();
+bool VideoRendererImpl::ShouldTransitionToPrerolled() {
+  return state_ == kPrerolling &&
+         (!video_frame_stream_.CanReadWithoutStalling() ||
+          video_frame_count() >= limits::kMaxVideoFrames);
+}
+
+bool VideoRendererImpl::ShouldTransitionToEnded() {
+  return state_ == kPlaying && unscheduled_frames_.empty() &&
+         scheduled_frames_.empty() && received_end_of_stream_;
 }
 
-void VideoRendererImpl::AttemptRead_Locked() {
+void VideoRendererImpl::TransitionToEnded() {
+  DCHECK(ShouldTransitionToEnded());
+  state_ = kEnded;
+  ended_cb_.Run();
+}
+
+void VideoRendererImpl::AttemptRead() {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  lock_.AssertAcquired();
 
   if (pending_read_ || received_end_of_stream_ ||
-      ready_frames_.size() == static_cast<size_t>(limits::kMaxVideoFrames)) {
+      video_frame_count() == limits::kMaxVideoFrames) {
     return;
   }
 
@@ -470,41 +334,20 @@ void VideoRendererImpl::AttemptRead_Locked() {
 }
 
 void VideoRendererImpl::OnVideoFrameStreamResetDone() {
-  base::AutoLock auto_lock(lock_);
   if (state_ == kStopped)
     return;
 
   DCHECK_EQ(kFlushing, state_);
   DCHECK(!pending_read_);
-  DCHECK(ready_frames_.empty());
+  DCHECK(unscheduled_frames_.empty());
+  DCHECK(scheduled_frames_.empty());
   DCHECK(!received_end_of_stream_);
 
   state_ = kFlushed;
-  last_timestamp_ = kNoTimestamp();
   base::ResetAndReturn(&flush_cb_).Run();
 }
 
-base::TimeDelta VideoRendererImpl::CalculateSleepDuration(
-    const scoped_refptr<VideoFrame>& next_frame,
-    float playback_rate) {
-  // Determine the current and next presentation timestamps.
-  base::TimeDelta now = get_time_cb_.Run();
-  base::TimeDelta next_pts = next_frame->timestamp();
-
-  // Scale our sleep based on the playback rate.
-  base::TimeDelta sleep = next_pts - now;
-  return base::TimeDelta::FromMicroseconds(
-      static_cast<int64>(sleep.InMicroseconds() / playback_rate));
-}
-
-void VideoRendererImpl::DoStopOrError_Locked() {
-  lock_.AssertAcquired();
-  last_timestamp_ = kNoTimestamp();
-  ready_frames_.clear();
-}
-
-void VideoRendererImpl::TransitionToPrerolled_Locked() {
-  lock_.AssertAcquired();
+void VideoRendererImpl::TransitionToPrerolled() {
   DCHECK_EQ(state_, kPrerolling);
 
   state_ = kPrerolled;
@@ -512,29 +355,113 @@ void VideoRendererImpl::TransitionToPrerolled_Locked() {
   // Because we might remain in the prerolled state for an undetermined amount
   // of time (e.g., we seeked while paused), we'll paint the first prerolled
   // frame.
-  if (!ready_frames_.empty())
-    PaintNextReadyFrame_Locked();
+  if (!unscheduled_frames_.empty()) {
+    ScheduleFirstFrameForImmediateDisplay();
+    AttemptRead();
+  }
 
   base::ResetAndReturn(&preroll_cb_).Run(PIPELINE_OK);
 }
 
-void VideoRendererImpl::UpdateStatsAndWait_Locked(
-    base::TimeDelta wait_duration) {
-  lock_.AssertAcquired();
-  DCHECK_GE(frames_decoded_, 0);
-  DCHECK_LE(frames_dropped_, frames_decoded_);
+void VideoRendererImpl::ResetScheduler() {
+  for (VideoFrameIDMap::iterator iter = scheduled_frames_.begin();
+       iter != scheduled_frames_.end();
+       ++iter) {
+    unscheduled_frames_.push_back(iter->second);
+  }

[xhwang, 2014/04/25 05:44:47]

With all the asyncness, it's not a surprise that a frame pushed back here has
actually already been displayed.  What's the plan here? How can we make sure
that a frame that's been displayed (expired) will not be displayed again?

[scherkus (not reviewing), 2014/04/25 18:24:25]

It's very possible we'll need to introduce more waiting/coordination between the
VFS and VRI.

I have some ideas on how to fix the SetPlaybackRate() issue, but I'm trying to
think through other scenarios where we reset the scheduler that could lead to
duplicate frame displays.

+  scheduled_frames_.clear();
+  scheduler_->Reset();
+}
+
+void VideoRendererImpl::ScheduleAllFrames() {
+  DCHECK_EQ(state_, kPlaying);
+
+  if (playback_rate_ == 0)
+    return;
+
+  base::TimeDelta current_media_time = get_time_cb_.Run();
+  base::TimeTicks current_wall_ticks = tick_clock_->NowTicks();
+
+  while (!unscheduled_frames_.empty()) {
+    // Negative deltas are permitted as it's up to the scheduler to decide
+    // what it wants to do with late frames.
+    base::TimeDelta delta =
+        unscheduled_frames_.front()->timestamp() - current_media_time;
+    base::TimeDelta scaled_delta = base::TimeDelta::FromMicroseconds(
+        static_cast<int64>(delta.InMicroseconds() / playback_rate_));
+    base::TimeTicks target_wall_ticks = current_wall_ticks + scaled_delta;
+
+    scoped_refptr<VideoFrame> frame = unscheduled_frames_.front();
+    int frame_id = next_scheduled_frame_id_++;
+    scheduled_frames_[frame_id] = frame;
+    unscheduled_frames_.pop_front();
+
+    scheduler_->ScheduleVideoFrame(
+        frame,
+        target_wall_ticks,
+        base::Bind(&VideoRendererImpl::OnVideoFrameFinished,
+                   weak_factory_.GetWeakPtr(),
+                   frame_id));
+  }
+}
+
+void VideoRendererImpl::ScheduleFirstFrameForImmediateDisplay() {
+  DCHECK_EQ(state_, kPrerolled);
+
+  scoped_refptr<VideoFrame> frame = unscheduled_frames_.front();
+  int frame_id = next_scheduled_frame_id_++;
+  scheduled_frames_[frame_id] = frame;
+  unscheduled_frames_.pop_front();
+
+  scheduler_->ScheduleVideoFrame(
+      frame,
+      tick_clock_->NowTicks(),
+      base::Bind(&VideoRendererImpl::OnVideoFrameFinished,
+                 weak_factory_.GetWeakPtr(),
+                 frame_id));
+}
+
+void VideoRendererImpl::OnVideoFrameFinished(
+    int frame_id,
+    const scoped_refptr<VideoFrame>& frame,
+    VideoFrameScheduler::Reason reason) {
+  VideoFrameIDMap::iterator iter = scheduled_frames_.find(frame_id);
+  if (iter == scheduled_frames_.end()) {
+    LOG(ERROR) << "Ignoring frame_id=" << frame_id

[scherkus (not reviewing), 2014/04/25 02:04:47]

note to self: remove

+             << ", timestamp=" << frame->timestamp().InMicroseconds();
+    return;
+  }
+
+  CHECK_EQ(iter->second, frame);
+  scheduled_frames_.erase(iter);
 
-  if (frames_decoded_) {
-    PipelineStatistics statistics;
-    statistics.video_frames_decoded = frames_decoded_;
-    statistics.video_frames_dropped = frames_dropped_;
-    statistics_cb_.Run(statistics);
+  switch (reason) {
+    case VideoFrameScheduler::DISPLAYED:
+      ++frames_decoded_;
+      break;
 
-    frames_decoded_ = 0;
-    frames_dropped_ = 0;
+    case VideoFrameScheduler::DROPPED:
+      ++frames_decoded_;
+      ++frames_dropped_;
+      break;
   }
 
-  frame_available_.TimedWait(wait_duration);
+  PipelineStatistics stats;
+  stats.video_frames_decoded = frames_decoded_;
+  stats.video_frames_dropped = frames_dropped_;
+  statistics_cb_.Run(stats);
+
+  if (ShouldTransitionToEnded()) {
+    TransitionToEnded();
+    return;
+  }
+
+  AttemptRead();
+}
+
+void VideoRendererImpl::SetTickClockForTesting(
+    scoped_ptr<base::TickClock> tick_clock) {
+  tick_clock_.swap(tick_clock);
 }
 
 }  // namespace media