mustash: Use ui::chromeos::EventRewriter in mus

ui/events/event_sink.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_EVENTS_EVENT_SINK_H_
+#define UI_EVENTS_EVENT_SINK_H_
+
+#include "ui/events/event_dispatcher.h"
+
+namespace ui {
+
+class Event;
+
+// EventSink receives events from an EventSource.
+class EVENTS_EXPORT EventSink {
+ public:
+  virtual ~EventSink() {}
+
+  // Receives events from EventSource.
+  virtual EventDispatchDetails OnEventFromSource(Event* event)
+      WARN_UNUSED_RESULT = 0;
+};
+
+}  // namespace ui
+
+#endif  // UI_EVENTS_EVENT_SINK_H_