Adds mojom structure for ui::Accelerator and struct traits

ui/base/accelerators/mojo/accelerator_struct_traits_unittest.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/base/accelerators/mojo/accelerator_struct_traits.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/base/accelerators/accelerator.h"
+#include "ui/base/accelerators/mojo/accelerator.mojom.h"
+#include "ui/events/event_constants.h"
+
+namespace ui {
+
+TEST(AcceleratorStructTraitsTest, SerializeAndDeserialize1) {
+  Accelerator accelerator(KeyboardCode::VKEY_TAB, EF_NUM_LOCK_ON);
+  accelerator.set_key_state(ui::Accelerator::KeyState::RELEASED);
+  Accelerator deserialized;
+  ASSERT_TRUE(mojom::Accelerator::Deserialize(
+      mojom::Accelerator::Serialize(&accelerator), &deserialized));
+  EXPECT_EQ(accelerator, deserialized);
+}
+
+TEST(AcceleratorStructTraitsTest, SerializeAndDeserialize2) {
+  const Accelerator accelerator(KeyboardCode::VKEY_SPACE, EF_SHIFT_DOWN);
+  Accelerator deserialized;
+  ASSERT_TRUE(mojom::Accelerator::Deserialize(
+      mojom::Accelerator::Serialize(&accelerator), &deserialized));
+  EXPECT_EQ(accelerator, deserialized);
+}
+
+}  // namespace ui