Add StructTraits for AcceleratedWidget instances.

ui/gfx/mojo/accelerated_widget_struct_traits.h

Index: ui/gfx/mojo/accelerated_widget_struct_traits.h
diff --git a/ui/gfx/mojo/accelerated_widget_struct_traits.h b/ui/gfx/mojo/accelerated_widget_struct_traits.h
new file mode 100644
index 0000000000000000000000000000000000000000..efa02a2b039de153a78ee3ad36df19805f78070a
--- /dev/null
+++ b/ui/gfx/mojo/accelerated_widget_struct_traits.h
@@ -0,0 +1,39 @@
+// 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 UI_GFX_MOJO_ACCELERATED_WIDGET_STRUCT_TRAITS_H_
+#define UI_GFX_MOJO_ACCELERATED_WIDGET_STRUCT_TRAITS_H_
+
+#include "ui/gfx/mojo/accelerated_widget.mojom.h"
+#include "ui/gfx/native_widget_types.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<gfx::mojom::AcceleratedWidget, gfx::AcceleratedWidget> {
+  static uint64_t widget(const gfx::AcceleratedWidget& widget) {
+#if defined(OS_WIN) || defined(USE_OZONE) || defined(USE_X11)
+    return uint64_t(widget);

[dcheng, 2016/06/22 14:18:08]

Nit: static_cast here and below rather than using a function-style cast.

+#else
+    NOTIMPLEMENTED();
+    return 0;
+#endif
+  }
+
+  static bool Read(gfx::mojom::AcceleratedWidgetDataView data,
+                   gfx::AcceleratedWidget* out) {
+#if defined(OS_WIN) || defined(USE_OZONE) || defined(USE_X11)
+    uint64_t w = data.widget();
+    *out = gfx::AcceleratedWidget(w);
+#else
+    NOTIMPLEMENTED();
+    *out = 0;
+#endif
+    return true;
+  }
+};
+
+}  // namespace mojo
+
+#endif  // UI_GFX_MOJO_ACCELERATED_WIDGET_STRUCT_TRAITS_H_