Use mojo typemap to simplify the code using DmabufPlane

components/arc/video_accelerator/video_accelerator_struct_traits.cc

Index: components/arc/video_accelerator/video_accelerator_struct_traits.cc
diff --git a/components/arc/video_accelerator/video_accelerator_struct_traits.cc b/components/arc/video_accelerator/video_accelerator_struct_traits.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3feb966d8af5945eb215abd0145c92a85bae8bdb
--- /dev/null
+++ b/components/arc/video_accelerator/video_accelerator_struct_traits.cc
@@ -0,0 +1,23 @@
+// 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.
+
+#include "components/arc/video_accelerator/video_accelerator_struct_traits.h"
+
+namespace mojo {
+
+// static
+bool StructTraits<arc::mojom::ArcVideoAcceleratorDmabufPlaneDataView,
+                  arc::ArcVideoAcceleratorDmabufPlane>::
+    Read(arc::mojom::ArcVideoAcceleratorDmabufPlaneDataView data,
+         arc::ArcVideoAcceleratorDmabufPlane* out) {
+  if (data.offset() < 0 || data.stride() < 0) {
+    return false;
+  }
+
+  out->offset = data.offset();
+  out->stride = data.stride();
+  return true;
+}
+
+}  // namespace mojo