[ozone/wayland] Implement basic keyboard handling support

ui/ozone/platform/wayland/wayland_xkb_keyboard_layout_engine.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/ozone/platform/wayland/wayland_xkb_keyboard_layout_engine.h"
+
+#include "ui/events/event_constants.h"
+
+namespace ui {
+
+WaylandXkbKeyboardLayoutEngine::WaylandXkbKeyboardLayoutEngine(
+    const XkbKeyCodeConverter& converter)
+    : XkbKeyboardLayoutEngine(converter) {}
+
+void WaylandXkbKeyboardLayoutEngine::SetKeymap(xkb_keymap* keymap) {
+  XkbKeyboardLayoutEngine::SetKeymap(keymap);
+
+  xkb_mod_indexes_.control =
+      xkb_keymap_mod_get_index(keymap, XKB_MOD_NAME_CTRL);
+  xkb_mod_indexes_.alt = xkb_keymap_mod_get_index(keymap, XKB_MOD_NAME_ALT);
+  xkb_mod_indexes_.shift = xkb_keymap_mod_get_index(keymap, XKB_MOD_NAME_SHIFT);
+}
+
+int WaylandXkbKeyboardLayoutEngine::UpdateModifiers(uint32_t depressed_mods,
+                                                    uint32_t latched_mods,
+                                                    uint32_t locked_mods,
+                                                    uint32_t group) {
+  xkb_state_update_mask(xkb_state_.get(), depressed_mods, latched_mods,
+                        locked_mods, 0, 0, group);
+
+  int modifiers = 0;
+  auto component = static_cast<xkb_state_component>(XKB_STATE_MODS_DEPRESSED |
+                                                    XKB_STATE_MODS_LATCHED);
+  if (xkb_state_mod_index_is_active(xkb_state_.get(), xkb_mod_indexes_.control,
+                                    component))
+    modifiers |= EF_CONTROL_DOWN;
+  if (xkb_state_mod_index_is_active(xkb_state_.get(), xkb_mod_indexes_.alt,
+                                    component))
+    modifiers |= EF_ALT_DOWN;
+  if (xkb_state_mod_index_is_active(xkb_state_.get(), xkb_mod_indexes_.shift,
+                                    component))
+    modifiers |= EF_SHIFT_DOWN;
+
+  return modifiers;
+}
+
+}  // namespace ui