MJPEG acceleration for video capture using VAAPI, the GPU host part

content/common/gpu/client/gpu_jpeg_decode_accelerator_host.h

+// Copyright 2015 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 CONTENT_COMMON_GPU_CLIENT_GPU_JPEG_DECODE_ACCELERATOR_HOST_H_
+#define CONTENT_COMMON_GPU_CLIENT_GPU_JPEG_DECODE_ACCELERATOR_HOST_H_
+
+#include "base/memory/weak_ptr.h"
+#include "base/threading/non_thread_safe.h"
+#include "media/video/jpeg_decode_accelerator.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace IPC {
+class Listener;
+class Message;
+}
+
+namespace content {
+class GpuChannelHost;
+
+// This class is used to talk to JpegDecodeAccelerator in the GPU process
+// through IPC messages.
+class GpuJpegDecodeAcceleratorHost : public media::JpegDecodeAccelerator,
+                                     public base::NonThreadSafe {
+ public:
+  // GpuJpegDecoder owns |this| and |channel|. And GpuJpegDecoder delete |this|
+  // before |channel|. So |this| is guaranteed not to outlive |channel|.
+  GpuJpegDecodeAcceleratorHost(
+      GpuChannelHost* channel,
+      int32 route_id,
+      const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner);
+  ~GpuJpegDecodeAcceleratorHost() override;
+
+  // media::JpegDecodeAccelerator implementation.
+  bool Initialize(media::JpegDecodeAccelerator::Client* client) override;

[piman, 2015/06/08 21:22:17]

nit: can you add a comment that the Client is called on the IO thread, but is
never called into after the GpuJpegDecodeAcceleratorHost is destroyed?

[kcwu, 2015/06/09 08:34:42]

Done.

+  void Decode(const media::BitstreamBuffer& bitstream_buffer,
+              const scoped_refptr<media::VideoFrame>& video_frame) override;
+
+  base::WeakPtr<IPC::Listener> GetReceiver();
+
+ private:
+  class Receiver;
+
+  void Send(IPC::Message* message);
+
+  // Unowned reference to the GpuChannelHost to send IPC messages to the GPU
+  // process.
+  GpuChannelHost* channel_;
+
+  // Route ID for the associated decoder in the GPU process.
+  int32 decoder_route_id_;
+
+  // GPU IO task runner.
+  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
+
+  scoped_ptr<Receiver> receiver_;
+
+  DISALLOW_COPY_AND_ASSIGN(GpuJpegDecodeAcceleratorHost);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_GPU_CLIENT_GPU_JPEG_DECODE_ACCELERATOR_HOST_H_