[ozone/wayland] Implement basic keyboard handling support

ui/ozone/platform/wayland/wayland_xkb_keyboard_layout_engine.h

+// 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.
+
+#ifndef UI_OZONE_PLATFORM_WAYLAND_WAYLAND_XKB_KEYBOARD_LAYOUT_ENGINE_H_
+#define UI_OZONE_PLATFORM_WAYLAND_WAYLAND_XKB_KEYBOARD_LAYOUT_ENGINE_H_
+
+#include "ui/events/ozone/layout/xkb/xkb_keyboard_layout_engine.h"
+
+#include "ui/events/ozone/layout/xkb/xkb_key_code_converter.h"
+
+namespace ui {
+
+class WaylandXkbKeyboardLayoutEngine : public XkbKeyboardLayoutEngine {
+ public:
+  WaylandXkbKeyboardLayoutEngine(const XkbKeyCodeConverter& converter);
+
+  // Used to sync up client side 'xkb_state' instance with modifiers status
+  // update from the compositor.
+  int UpdateModifiers(uint32_t depressed_mods,
+                      uint32_t latched_mods,
+                      uint32_t locked_mods,
+                      uint32_t group);
+
+ private:
+  void SetKeymap(xkb_keymap* keymap) override;
+
+  // Cache to access modifiers xkb_mode_index_t value.
+  struct {
+    xkb_mod_index_t control = 0;
+    xkb_mod_index_t alt = 0;
+    xkb_mod_index_t shift = 0;
+  } xkb_mod_indexes_;
+};
+
+}  // namespace ui
+
+#endif  // UI_EVENTS_OZONE_LAYOUT_XKB_XKB_KEYBOARD_LAYOUT_ENGINE_H_