Add VideoFrameRecorder for use recording test frame sequences.

remoting/host/video_frame_recorder.h

Index: remoting/host/video_frame_recorder.h
diff --git a/remoting/host/video_frame_recorder.h b/remoting/host/video_frame_recorder.h
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index 0000000000000000000000000000000000000000..61f7be78c268cecd5df3f435a3ff4a96eae04591
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+++ b/remoting/host/video_frame_recorder.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 REMOTING_HOST_VIDEO_FRAME_RECORDER_H_
+#define REMOTING_HOST_VIDEO_FRAME_RECORDER_H_
+
+#include <list>
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
+
+namespace webrtc {
+class DesktopFrame;
+}
+
+namespace remoting {
+
+class VideoEncoder;
+
+// Records video frames passed to a VideoEncoder.
+// Callers create VideoFrameRecorder instances and call WrapVideoEncoder() to
+// wrap an underlying VideoEncoder, and return a replacement VideoEncoder
+// instance that can be passed to the frame capture engine in its place.

[Sergey Ulanov, 2014/06/20 22:32:13]

Threading semantics is not very clear. It looks like all methods, including 
WrapVideoEncoder() must be called on the same thread, but the returned
VideoEncode can be called on a different thread.

[Wez, 2014/06/24 01:02:15]

Done.

+class VideoFrameRecorder {
+ public:
+  VideoFrameRecorder();
+  virtual ~VideoFrameRecorder();
+
+  // Wraps the supplied VideoEncoder, returning a replacement VideoEncoder that
+  // will route frames to the recorder, as well as passing them for encoding.

[Sergey Ulanov, 2014/06/20 22:32:13]

Looks like this function is not allowed to be called more than once (DCHECK in
VideoFrameRecorder::SetEncoderTaskRunner()). Comment should mention it.

[Wez, 2014/06/24 01:02:15]

Done.

+  scoped_ptr<VideoEncoder> WrapVideoEncoder(scoped_ptr<VideoEncoder> encoder);
+
+  // Enables/disables frame recording. Frame recording is initially disabled.
+  void SetEnableRecording(bool enable_recording);
+
+  // Sets the maximum number of bytes of pixel data that may be recorded.
+  // When this maximum is reached older frames will be discard to make space
+  // for new ones.
+  void SetMaxContentBytes(int64 max_content_bytes);

[Sergey Ulanov, 2014/06/20 22:32:13]

nit: not sure if it's documented anywhere, but it's better to use int64_t in new
code, instead of int64. E.g. current style guide doesn't even mention int64.

[Wez, 2014/06/24 01:02:15]

Done.

+
+  // Pops the next recorded frame in sequences, and returns it.
+  scoped_ptr<webrtc::DesktopFrame> NextFrame();
+
+ private:
+  class RecordingVideoEncoder;
+  friend class RecordingVideoEncoder;
+
+  void SetEncoderTaskRunner(scoped_refptr<base::TaskRunner> task_runner);
+  void RecordFrame(scoped_ptr<webrtc::DesktopFrame> frame);
+
+  // The recorded frames, in sequence.
+  std::list<webrtc::DesktopFrame*> recorded_frames_;
+
+  // Size of the recorded frames' content, in bytes.
+  int64 content_bytes_;
+
+  // Size that recorded frames' content must not exceed.
+  int64 max_content_bytes_;
+
+  // True if recording is started, false otherwise.
+  bool enable_recording_;
+
+  // Task runner on which the wrapper VideoEncoder is being run.
+  scoped_refptr<base::TaskRunner> encoder_task_runner_;
+
+  // Weak reference to the wrapper VideoEncoder, to use to control it.
+  base::WeakPtr<RecordingVideoEncoder> recording_encoder_;
+
+  scoped_refptr<base::SingleThreadTaskRunner> caller_task_runner_;
+  base::WeakPtrFactory<VideoFrameRecorder> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoFrameRecorder);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_VIDEO_FRAME_RECORDER_H_