Introduce VideoFrameScheduler{Impl}.

media/filters/video_frame_scheduler_proxy.h

Index: media/filters/video_frame_scheduler_proxy.h
diff --git a/media/filters/video_frame_scheduler_proxy.h b/media/filters/video_frame_scheduler_proxy.h
new file mode 100644
index 0000000000000000000000000000000000000000..d17fb5632bc3e9a3ce1dc32b4659e1f38b60b7f5
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+++ b/media/filters/video_frame_scheduler_proxy.h
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+// 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_PROXY_H_
+#define MEDIA_FILTERS_VIDEO_FRAME_SCHEDULER_PROXY_H_
+
+#include "base/memory/weak_ptr.h"
+#include "media/filters/video_frame_scheduler.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace media {
+
+// Provides a thread-safe proxy for a VideoFrameScheduler. Typical use is to
+// use a real VideoFrameScheduler on the task runner responsible for graphics
+// display and provide a proxy on the task runner responsible for background
+// video decoding.
+class MEDIA_EXPORT VideoFrameSchedulerProxy : public VideoFrameScheduler {
+ public:
+  // |task_runner| is the runner that this object will be called on.
+  // |scheduler_runner| is the runner that |scheduler| will be called on.
+  // |scheduler| must out-live the lifetime of this object.
+  VideoFrameSchedulerProxy(
+      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
+      const scoped_refptr<base::SingleThreadTaskRunner>& scheduler_runner,
+      VideoFrameScheduler* scheduler);
+  virtual ~VideoFrameSchedulerProxy();
+
+  // VideoFrameScheduler implementation.
+  virtual void ScheduleVideoFrame(const scoped_refptr<VideoFrame>& frame,
+                                  base::TimeTicks wall_ticks,
+                                  const DoneCB& done_cb) OVERRIDE;
+  virtual void Reset() OVERRIDE;
+
+ private:
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> scheduler_runner_;
+  VideoFrameScheduler* scheduler_;  // Not owned.
+
+  // NOTE: Weak pointers must be invalidated before all other member variables.
+  base::WeakPtrFactory<VideoFrameSchedulerProxy> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoFrameSchedulerProxy);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_VIDEO_FRAME_SCHEDULER_PROXY_H_