Keyboard Lock Host implementation

components/keyboard_lock/key_event_filter.h

Index: components/keyboard_lock/key_event_filter.h
diff --git a/components/keyboard_lock/key_event_filter.h b/components/keyboard_lock/key_event_filter.h
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index 0000000000000000000000000000000000000000..fbad987dc84a01dea6605e1c8af46402da88ba8d
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+// 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_EVENT_FILTER_H_
+#define COMPONENTS_KEYBOARD_LOCK_KEY_EVENT_FILTER_H_
+
+#include "ui/events/event_constants.h"
+#include "ui/events/keycodes/keyboard_codes.h"
+
+namespace keyboard_lock {
+
+// An interface to receive and process a key event. The implementation needs to
+// guarantee the thread-safety of OnKeyDown() and OnKeyUp() functions, which may
+// be executed in a unpredictable thread.
+class KeyEventFilter {
+ public:
+  KeyEventFilter() = default;
+  virtual ~KeyEventFilter() = default;
+
+  // Returns true if the |code| should be suppressed.
+  virtual bool OnKeyDown(ui::KeyboardCode code, int flags) = 0;
+
+  // REturns true if the |code| should be suppressed.
+  virtual bool OnKeyUp(ui::KeyboardCode code, int flags) = 0;
+};
+
+}  // namespace keyboard_lock
+
+#endif  // COMPONENTS_KEYBOARD_LOCK_KEY_EVENT_FILTER_H_