Created VideoFramePool to avoid unnecessary VideoFrame alloc/free.

media/base/video_frame_pool.h

Index: media/base/video_frame_pool.h
diff --git a/media/base/video_frame_pool.h b/media/base/video_frame_pool.h
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+// Copyright 2013 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_BASE_VIDEO_FRAME_POOL_H_
+#define MEDIA_BASE_VIDEO_FRAME_POOL_H_
+
+#include "media/base/media_export.h"
+#include "media/base/video_frame.h"
+
+namespace media {
+
+// Simple VideoFrame pool used to avoid unnecessarily allocating and destroying
+// VideoFrame objects. The pool manages the memory for the VideoFrame
+// returned by CreateFrame(). When one of these VideoFrames is destroyed,
+// the memory is returned to the pool for use by a subsequent CreateFrame()
+// call. The memory in the pool is retained for the life of the
+// VideoFramePool object. If the parameters passed to CreateFrame() change
+// during the life of this object, then the memory used by frames with the old
+// parameter values will be purged from the pool.
+class MEDIA_EXPORT VideoFramePool {
+ public:
+  VideoFramePool();
+  ~VideoFramePool();
+
+  // Returns a frame from the pool that matches the specified
+  // parameters or creates a new frame if no suitable frame exists in
+  // the pool.
+  scoped_refptr<VideoFrame> CreateFrame(VideoFrame::Format format,
+                                        const gfx::Size& coded_size,
+                                        const gfx::Rect& visible_rect,
+                                        const gfx::Size& natural_size,
+                                        base::TimeDelta timestamp);
+
+protected:
+  friend class VideoFramePoolTest;
+
+  // Returns the number of frames in the pool for testing purposes.
+  size_t GetPoolSizeForTesting() const;
+
+ private:
+  class PoolImpl;
+  scoped_refptr<PoolImpl> pool_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoFramePool);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_VIDEO_FRAME_POOL_H_