Use mojo typemap to simplify the code using DmabufPlane

components/arc/video_accelerator/video_accelerator_struct_traits.h

Index: components/arc/video_accelerator/video_accelerator_struct_traits.h
diff --git a/components/arc/video_accelerator/video_accelerator_struct_traits.h b/components/arc/video_accelerator/video_accelerator_struct_traits.h
new file mode 100644
index 0000000000000000000000000000000000000000..68e3befd80ff232f55d3a4ad85232b45e7ca11a8
--- /dev/null
+++ b/components/arc/video_accelerator/video_accelerator_struct_traits.h
@@ -0,0 +1,32 @@
+// 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_ACCELERATOR_VIDEO_ACCELERATOR_STRUCT_TRAITS_H_
+#define COMPONENTS_ARC_VIDEO_ACCELERATOR_VIDEO_ACCELERATOR_STRUCT_TRAITS_H_
+
+#include "components/arc/common/video_accelerator.mojom.h"
+#include "components/arc/video_accelerator/video_accelerator.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<arc::mojom::ArcVideoAcceleratorDmabufPlaneDataView,
+                    arc::ArcVideoAcceleratorDmabufPlane> {
+  static uint32_t offset(const arc::ArcVideoAcceleratorDmabufPlane& r) {
+    DCHECK(r.offset >= 0);
+    return r.offset;
+  }
+
+  static uint32_t stride(const arc::ArcVideoAcceleratorDmabufPlane& r) {
+    DCHECK(r.stride >= 0);
+    return r.stride;
+  }
+
+  static bool Read(arc::mojom::ArcVideoAcceleratorDmabufPlaneDataView data,
+                   arc::ArcVideoAcceleratorDmabufPlane* out);
+};
+
+}  // namespace mojo
+
+#endif  // COMPONENTS_ARC_VIDEO_ACCELERATOR_VIDEO_ACCELERATOR_STRUCT_TRAITS_H_