Build key map DomCodeToKey() for Windows

ui/events/keycodes/platform_key_map_win.h

+// Copyright (c) 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_EVENTS_KEYCODES_PLATFORM_KEY_MAP_WIN_H_
+#define UI_EVENTS_KEYCODES_PLATFORM_KEY_MAP_WIN_H_
+
+#include <windows.h>
+
+#include <unordered_map>
+
+#include "base/hash.h"
+#include "ui/events/events_base_export.h"
+#include "ui/events/keycodes/dom/dom_key.h"
+#include "ui/events/keycodes/keyboard_codes_win.h"
+
+namespace ui {
+
+enum class DomCode;
+
+class EVENTS_BASE_EXPORT PlatformKeyMap {
+ public:
+  // Create and load key map table with specified keyboard layout.
+  explicit PlatformKeyMap(HKL layout);
+
+  // Returns the DomKey 'meaning' of |code| in the context of specified
+  // |ui_event_flags| and stored keyboard layout.
+  DomKey DomCodeAndFlagsToDomKey(DomCode code,
+                                 int ui_event_flags) const;
+
+  // Returns the DomKey 'meaning' of |code| in the context of specified
+  // |ui_event_flags| and the keyboard layout of current thread.
+  // Updates a per-thread key map cache whenever the layout changes.
+  static DomKey DomCodeAndFlagsToDomKeyStatic(
+      DomCode code,
+      int ui_event_flags);
+
+ private:
+  PlatformKeyMap();
+
+  // TODO(chongz): Expose this function in response to WM_INPUTLANGCHANGE.
+  void UpdateLayout(HKL layout);
+
+  HKL keyboard_layout_ = 0;
+
+  // TODO(chongz): Change type to DomCode when we got a generic pair hash class.
+  typedef std::pair<int /*DomCode*/, int /*EventFlags*/> DomCodeEventFlagsPair;
+  typedef std::unordered_map<DomCodeEventFlagsPair,
+                             DomKey,
+                             base::IntPairHash<std::pair<int, int>>>
+      DomCodeToKeyMap;
+  DomCodeToKeyMap code_to_key_;
+
+  DISALLOW_COPY_AND_ASSIGN(PlatformKeyMap);
+};
+
+}  // namespace ui
+
+#endif  // UI_EVENTS_KEYCODES_PLATFORM_KEY_MAP_WIN_H_