aura: Introduce EventInjector.

ui/aura/event_injector.h

Index: ui/aura/event_injector.h
diff --git a/ui/aura/event_injector.h b/ui/aura/event_injector.h
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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 UI_AURA_EVENT_INJECTOR_H_
+#define UI_AURA_EVENT_INJECTOR_H_
+
+#include "services/ui/public/interfaces/window_server_test.mojom.h"
+#include "ui/aura/aura_export.h"
+
+namespace ui {
+class Event;
+struct EventDispatchDetails;
+}
+
+namespace aura {
+
+class WindowTreeHost;
+
+// Used to inject events into the system. In LOCAL mode, it directly injects
+// events into the WindowTreeHost, but in MUS mode, it injects events into the
+// window-server (over the mojom API).
+class AURA_EXPORT EventInjector {
+ public:
+  EventInjector();
+  ~EventInjector();
+
+  ui::EventDispatchDetails Inject(WindowTreeHost* host, ui::Event* event);
+
+ private:
+  ui::mojom::WindowServerTestPtr window_server_ptr_;
+
+  DISALLOW_COPY_AND_ASSIGN(EventInjector);
+};
+
+}  // namespace aura
+
+#endif  // UI_AURA_EVENT_INJECTOR_H_