Implement GpuArcVideoService for arc video accelerator

content/browser/gpu/gpu_arc_video_service_host.h

+// Copyright 2016 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_BROWSER_GPU_GPU_ARC_VIDEO_SERVICE_HOST_H_
+#define CONTENT_BROWSER_GPU_GPU_ARC_VIDEO_SERVICE_HOST_H_
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/threading/thread_checker.h"
+#include "components/arc/video/video_host_delegate.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace IPC {
+struct ChannelHandle;
+}
+
+namespace content {
+
+// This class passes requests from arc::VideoInstance to GpuArcVideoService to
+// create a video accelerator channel in GPU process and reply the created
+// channel.
+//
+// Don't be confused two senses of "host" of this class. This class, which
+// implements arc::VideoHost, handles requests from arc::VideoInstance. At the
+// same time, as its name says, this class is the host of corresponding class,
+// GpuArcVideoService, in the GPU process.
+class GpuArcVideoServiceHost : public arc::VideoHostDelegate {
+ public:
+  GpuArcVideoServiceHost();
+  ~GpuArcVideoServiceHost() override;
+
+  // arc::VideoHostDelegate implementation.
+  void OnStopping() override;
+
+  // arc::VideoHost implementation.
+  void OnRequestArcVideoAcceleratorChannel(
+      const OnRequestArcVideoAcceleratorChannelCallback& callback) override;
+
+ private:
+  base::ThreadChecker thread_checker_;
+
+  // IO task runner, where GpuProcessHost tasks run.
+  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(GpuArcVideoServiceHost);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_GPU_GPU_ARC_VIDEO_SERVICE_HOST_H_