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

ui/events/event_sink.h

Index: ui/events/event_sink.h
diff --git a/ui/events/event_sink.h b/ui/events/event_sink.h
new file mode 100644
index 0000000000000000000000000000000000000000..e31c1be2815c4c2c72f441814d5a1c6490794c73
--- /dev/null
+++ b/ui/events/event_sink.h
@@ -0,0 +1,26 @@
+// 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;

[sky, 2017/03/20 15:42:13]

Given mus seems to not care about the return value, is it really necessary to
have WARN_UNUSED_RESULT?

[Peng, 2017/03/20 17:24:14]

Remove it. Done

[sadrul, 2017/03/22 19:52:37]

This has been useful to prevent uaf in aura when windows/hosts are destroyed
during the processing of an event. I would prefer that we have this, and use
ignore_result() where we don't need the return value.

+};
+
+}  // namespace ui
+
+#endif  // UI_EVENTS_EVENT_SINK_H_