Implement GpuArcVideoService for arc video accelerator

components/arc/video/video_host_delegate.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 COMPONENTS_ARC_VIDEO_VIDEO_HOST_DELEGATE_H
+#define COMPONENTS_ARC_VIDEO_VIDEO_HOST_DELEGATE_H
+
+#include "components/arc/common/video.mojom.h"
+
+namespace arc {
+
+// VideoHostDelegate is an abstract class providing video decoding/encoding
+// acceleration service.
+//
+// The purpose of this interface is to create a channel into the GPU process
+// only, which then handles video decoding/encoding, without going through
+// VideoHostDelegate anymore.
+class VideoHostDelegate : public VideoHost {
+ public:
+  // Called when the video service is stopping.
+  virtual void OnStopping() = 0;
+};
+
+}  // namespace arc
+
+#endif  // COMPONENTS_ARC_VIDEO_VIDEO_HOST_DELEGATE_H