Refactor VideoRendererImpl to use VideoFrameScheduler.

media/filters/video_renderer_impl.h

Index: media/filters/video_renderer_impl.h
diff --git a/media/filters/video_renderer_impl.h b/media/filters/video_renderer_impl.h
index 014799a7567ec674d65e31109eabe3498c764e28..9daef0128a91dba7f902832ea6e981551bfef5ad 100644
--- a/media/filters/video_renderer_impl.h
+++ b/media/filters/video_renderer_impl.h
@@ -6,53 +6,32 @@
 #define MEDIA_FILTERS_VIDEO_RENDERER_IMPL_H_
 
 #include <deque>
+#include <map>
 
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
-#include "base/synchronization/condition_variable.h"
-#include "base/synchronization/lock.h"
-#include "base/threading/platform_thread.h"
 #include "media/base/decryptor.h"
-#include "media/base/demuxer_stream.h"
-#include "media/base/pipeline_status.h"
 #include "media/base/video_decoder.h"
-#include "media/base/video_frame.h"
 #include "media/base/video_renderer.h"
 #include "media/filters/decoder_stream.h"
+#include "media/filters/video_frame_scheduler.h"
 
 namespace base {
 class SingleThreadTaskRunner;
+class TickClock;
 }
 
 namespace media {
 
-// VideoRendererImpl creates its own thread for the sole purpose of timing frame
-// presentation.  It handles reading from the VideoFrameStream and stores the
-// results in a queue of decoded frames and executing a callback when a frame is
-// ready for rendering.
-class MEDIA_EXPORT VideoRendererImpl
-    : public VideoRenderer,
-      public base::PlatformThread::Delegate {
+// VideoRendererImpl is the state machine glue that handles reading from a
+// VideoFrameStream and scheduling frames to a VideoFrameScheduler.
+class MEDIA_EXPORT VideoRendererImpl : public VideoRenderer {
  public:
-  typedef base::Callback<void(const scoped_refptr<VideoFrame>&)> PaintCB;
-
   // |decoders| contains the VideoDecoders to use when initializing.
-  //
-  // |paint_cb| is executed on the video frame timing thread whenever a new
-  // frame is available for painting.
-  //
-  // Implementors should avoid doing any sort of heavy work in this method and
-  // instead post a task to a common/worker thread to handle rendering.  Slowing
-  // down the video thread may result in losing synchronization with audio.
-  //
-  // Setting |drop_frames_| to true causes the renderer to drop expired frames.
   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);
   virtual ~VideoRendererImpl();
 
   // VideoRenderer implementation.
@@ -72,8 +51,7 @@ class MEDIA_EXPORT VideoRendererImpl
   virtual void Stop(const base::Closure& callback) OVERRIDE;
   virtual void SetPlaybackRate(float playback_rate) OVERRIDE;
 
-  // PlatformThread::Delegate implementation.
-  virtual void ThreadMain() OVERRIDE;
+  void SetTickClockForTesting(scoped_ptr<base::TickClock> tick_clock);
 
  private:
   // Callback for |video_frame_stream_| initialization.
@@ -84,69 +62,54 @@ class MEDIA_EXPORT VideoRendererImpl
   void FrameReady(VideoFrameStream::Status status,
                   const scoped_refptr<VideoFrame>& frame);
 
-  // Helper method for adding a frame to |ready_frames_|.
-  void AddReadyFrame_Locked(const scoped_refptr<VideoFrame>& frame);
-
   // Helper method that schedules an asynchronous read from the
   // |video_frame_stream_| as long as there isn't a pending read and we have
   // capacity.
   void AttemptRead();
-  void AttemptRead_Locked();
 
   // Called when VideoFrameStream::Reset() completes.
   void OnVideoFrameStreamResetDone();
 
-  // Calculates the duration to sleep for based on |last_timestamp_|,
-  // the next frame timestamp (may be NULL), and the provided playback rate.
-  //
-  // We don't use |playback_rate_| to avoid locking.
-  base::TimeDelta CalculateSleepDuration(
-      const scoped_refptr<VideoFrame>& next_frame,
-      float playback_rate);
-
-  // Helper function that flushes the buffers when a Stop() or error occurs.
-  void DoStopOrError_Locked();
+  bool ShouldTransitionToPrerolled();
+  void TransitionToPrerolled();
 
-  // Runs |paint_cb_| with the next frame from |ready_frames_|.
-  //
-  // A read is scheduled to replace the frame.
-  void PaintNextReadyFrame_Locked();
+  bool ShouldTransitionToEnded();
+  void TransitionToEnded();
 
-  // Drops the next frame from |ready_frames_| and runs |statistics_cb_|.
-  //
-  // A read is scheduled to replace the frame.
-  void DropNextReadyFrame_Locked();
+  void ResetScheduler();
+  void ScheduleAllFrames();
+  void ScheduleFirstFrameForImmediateDisplay();
 
-  void TransitionToPrerolled_Locked();
+  void OnVideoFrameFinished(int frame_id,
+                            const scoped_refptr<VideoFrame>& frame,
+                            VideoFrameScheduler::Reason reason);
 
-  // Returns true of all conditions have been met to transition from
-  // kPrerolling to kPrerolled.
-  bool ShouldTransitionToPrerolled_Locked();
-
-  // Runs |statistics_cb_| with |frames_decoded_| and |frames_dropped_|, resets
-  // them to 0, and then waits on |frame_available_| for up to the
-  // |wait_duration|.
-  void UpdateStatsAndWait_Locked(base::TimeDelta wait_duration);
+  int video_frame_count() {
+    return static_cast<int>(unscheduled_frames_.size() +
+                            scheduled_frames_.size());
+  }
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
-  // Used for accessing data members.
-  base::Lock lock_;
+  scoped_ptr<VideoFrameScheduler> scheduler_;
+
+  scoped_ptr<base::TickClock> tick_clock_;
 
   // Provides video frames to VideoRendererImpl.
   VideoFrameStream video_frame_stream_;
 
-  // Queue of incoming frames yet to be painted.
+  // Unscheduled frames are stored FIFO in a queue. When a frame is scheduled
+  // it is assigned a unique ID and stored in a map. IDs are used to ensure we
+  // don't double count decoded/dropped frames for a particular frame.
   typedef std::deque<scoped_refptr<VideoFrame> > VideoFrameQueue;
-  VideoFrameQueue ready_frames_;
+  typedef std::map<int, scoped_refptr<VideoFrame> > VideoFrameIDMap;
+  VideoFrameQueue unscheduled_frames_;
+  VideoFrameIDMap scheduled_frames_;
+  int next_scheduled_frame_id_;
 
   // Keeps track of whether we received the end of stream buffer.
   bool received_end_of_stream_;
 
-  // Used to signal |thread_| as frames are added to |frames_|.  Rule of thumb:
-  // always check |state_| to see if it was set to STOPPED after waking up!
-  base::ConditionVariable frame_available_;
-
   // State transition Diagram of this class:
   //       [kUninitialized] -------> [kError]
   //              |
@@ -188,15 +151,10 @@ class MEDIA_EXPORT VideoRendererImpl
   };
   State state_;
 
-  // Video thread handle.
-  base::PlatformThreadHandle thread_;
-
   // Keep track of the outstanding read on the VideoFrameStream. Flushing can
   // only complete once the read has completed.
   bool pending_read_;
 
-  bool drop_frames_;
-
   float playback_rate_;
 
   // Playback operation callbacks.
@@ -214,16 +172,6 @@ class MEDIA_EXPORT VideoRendererImpl
 
   base::TimeDelta preroll_timestamp_;
 
-  // Embedder callback for notifying a new frame is available for painting.
-  PaintCB paint_cb_;
-
-  // The timestamp of the last frame removed from the |ready_frames_| queue,
-  // either for calling |paint_cb_| or for dropping. Set to kNoTimestamp()
-  // during flushing.
-  base::TimeDelta last_timestamp_;
-
-  // Keeps track of the number of frames decoded and dropped since the
-  // last call to |statistics_cb_|. These must be accessed under lock.
   int frames_decoded_;
   int frames_dropped_;