Introduce VideoFrameScheduler{Impl}.

media/filters/video_frame_scheduler_impl.h

Index: media/filters/video_frame_scheduler_impl.h
diff --git a/media/filters/video_frame_scheduler_impl.h b/media/filters/video_frame_scheduler_impl.h
new file mode 100644
index 0000000000000000000000000000000000000000..f6bc78dd2751b28a94583a3dc61ac8c1d8e565d7
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+++ b/media/filters/video_frame_scheduler_impl.h
@@ -0,0 +1,74 @@
+// Copyright 2014 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 MEDIA_FILTERS_VIDEO_FRAME_SCHEDULER_IMPL_H_
+#define MEDIA_FILTERS_VIDEO_FRAME_SCHEDULER_IMPL_H_
+
+#include <queue>
+
+#include "base/memory/ref_counted.h"
+#include "base/timer/timer.h"
+#include "media/filters/video_frame_scheduler.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+class TickClock;
+}
+
+namespace media {
+
+// A scheduler that uses delayed tasks on a task runner for timing the display
+// of video frames.
+//
+// Single threaded. Calls must be on |task_runner|.
+class MEDIA_EXPORT VideoFrameSchedulerImpl : public VideoFrameScheduler {
+ public:
+  typedef base::Callback<void(const scoped_refptr<VideoFrame>&)> DisplayCB;
+
+  // |task_runner| is used for scheduling the delayed tasks.
+  // |display_cb| is run when a frame is to be displayed.
+  VideoFrameSchedulerImpl(
+      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
+      const DisplayCB& display_cb);
+  virtual ~VideoFrameSchedulerImpl();
+
+  // VideoFrameScheduler implementation.
+  virtual void ScheduleVideoFrame(const scoped_refptr<VideoFrame>& frame,
+                                  base::TimeTicks wall_ticks,
+                                  const DoneCB& done_cb) OVERRIDE;
+  virtual void Reset() OVERRIDE;
+
+  void SetTickClockForTesting(scoped_ptr<base::TickClock> tick_clock);
+
+ private:
+  void ResetTimerIfNecessary();
+  void OnTimerFired();
+
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  DisplayCB display_cb_;
+  scoped_ptr<base::TickClock> tick_clock_;
+  base::OneShotTimer<VideoFrameScheduler> timer_;
+
+  struct PendingFrame {
+    PendingFrame(const scoped_refptr<VideoFrame>& frame,
+                 base::TimeTicks wall_ticks,
+                 const DoneCB& done_cb);
+    ~PendingFrame();
+
+    // For use with std::priority_queue<T>.
+    bool operator<(const PendingFrame& other) const;
+
+    scoped_refptr<VideoFrame> frame;
+    base::TimeTicks wall_ticks;
+    DoneCB done_cb;
+  };
+  typedef std::priority_queue<PendingFrame> PendingFrameQueue;
+  PendingFrameQueue pending_frames_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoFrameSchedulerImpl);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_VIDEO_FRAME_SCHEDULER_IMPL_H_