Update VideoFrameScheduler API and add clockless and testing implementations.

media/filters/clockless_video_frame_scheduler.h

+// 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_CLOCKLESS_VIDEO_FRAME_SCHEDULER_H_
+#define MEDIA_FILTERS_CLOCKLESS_VIDEO_FRAME_SCHEDULER_H_
+
+#include "media/filters/video_frame_scheduler.h"
+
+namespace media {
+
+// A scheduler that immediately displays frames.
+class ClocklessVideoFrameScheduler : public VideoFrameScheduler {
+ public:
+  typedef base::Callback<void(const scoped_refptr<VideoFrame>&)> DisplayCB;
+
+  explicit ClocklessVideoFrameScheduler(const DisplayCB& display_cb);
+  virtual ~ClocklessVideoFrameScheduler();
+
+  // VideoFrameScheduler implementation.
+  virtual void ScheduleVideoFrame(const scoped_refptr<VideoFrame>& frame,
+                                  base::TimeTicks wall_ticks,
+                                  const DoneCB& done_cb) OVERRIDE;
+  virtual void Reset() OVERRIDE;
+
+ private:
+  DisplayCB display_cb_;
+
+  DISALLOW_COPY_AND_ASSIGN(ClocklessVideoFrameScheduler);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_CLOCKLESS_VIDEO_FRAME_SCHEDULER_H_