Write mojom and StructTraits for DisplaySnapshot.

ui/display/mojo/display_mode_struct_traits.cc

+// Copyright 2017 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 "ui/display/mojo/display_mode_struct_traits.h"
+
+#include "ui/gfx/geometry/mojo/geometry_struct_traits.h"
+
+namespace mojo {
+
+// static
+bool StructTraits<display::mojom::DisplayModeDataView,
+                  std::unique_ptr<display::DisplayMode>>::
+    Read(display::mojom::DisplayModeDataView data,
+         std::unique_ptr<display::DisplayMode>* out) {
+  gfx::Size size;
+  if (!data.ReadSize(&size))
+    return false;
+  *out = base::MakeUnique<display::DisplayMode>(size, data.is_interlaced(),
+                                                data.refresh_rate());
+  return true;
+};
+
+}  // namespace mojo