Keyboard Lock Host implementation

components/keyboard_lock/key_hook_state_keeper.h

Index: components/keyboard_lock/key_hook_state_keeper.h
diff --git a/components/keyboard_lock/key_hook_state_keeper.h b/components/keyboard_lock/key_hook_state_keeper.h
new file mode 100644
index 0000000000000000000000000000000000000000..bf66a927787da37512bdc48655e4c9393d9f2fd6
--- /dev/null
+++ b/components/keyboard_lock/key_hook_state_keeper.h
@@ -0,0 +1,47 @@
+// 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 COMPONENTS_KEYBOARD_LOCK_KEY_HOOK_STATE_KEEPER_H_
+#define COMPONENTS_KEYBOARD_LOCK_KEY_HOOK_STATE_KEEPER_H_
+
+#include <memory>
+#include <vector>
+
+#include "components/keyboard_lock/key_event_filter.h"
+#include "components/keyboard_lock/key_hook_activator.h"
+
+namespace keyboard_lock {
+
+// An implementation of both KeyHookActivator and KeyEventFilter by maintaining
+// the internal states and filtering out unregistered key codes.
+class KeyHookStateKeeper final
+    : public KeyEventFilter,
+      public KeyHookActivator {
+ public:
+  KeyHookStateKeeper(std::unique_ptr<KeyEventFilter> filter,
+                     std::unique_ptr<KeyHook> key_hook);
+  ~KeyHookStateKeeper() override;
+
+  // KeyEventFilter implementations.
+  bool OnKeyDown(ui::KeyboardCode code, int flags) override;
+  bool OnKeyUp(ui::KeyboardCode code, int flags) override;
+
+  // KeyHookActivator implementations.
+  void RegisterKey(const std::vector<ui::KeyboardCode>& codes,
+                   base::Callback<void(bool)> on_result) override;
+  void UnregisterKey(const std::vector<ui::KeyboardCode>& codes,
+                     base::Callback<void(bool)> on_result) override;
+  void Activate(base::Callback<void(bool)> on_result) override;
+  void Deactivate(base::Callback<void(bool)> on_result) override;
+
+ private:
+  const std::unique_ptr<KeyEventFilter> filter_;
+  const std::unique_ptr<KeyHook> key_hook_;
+  std::vector<bool> states_;
+  bool active_;
+};
+
+}  // namespace keyboard_lock
+
+#endif  // COMPONENTS_KEYBOARD_LOCK_KEY_HOOK_STATE_KEEPER_H_