ui: Cleanup class/struct forward declarations

ui/events/ozone/evdev/input_injector_evdev.h

 // Copyright 2014 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_OZONE_EVDEV_INPUT_INJECTOR_EVDEV_H_
 #define UI_EVENTS_OZONE_EVDEV_INPUT_INJECTOR_EVDEV_H_
 
 #include "base/macros.h"
 #include "ui/events/ozone/evdev/event_dispatch_callback.h"
 #include "ui/events/ozone/evdev/events_ozone_evdev_export.h"
 #include "ui/ozone/public/system_input_injector.h"
 
 namespace ui {
 
-class Event;
 class CursorDelegateEvdev;
 class DeviceEventDispatcherEvdev;
 
 class EVENTS_OZONE_EVDEV_EXPORT InputInjectorEvdev
     : public SystemInputInjector {
  public:
   InputInjectorEvdev(std::unique_ptr<DeviceEventDispatcherEvdev> dispatcher,
                      CursorDelegateEvdev* cursor);
 
   ~InputInjectorEvdev() override;
@@ skipping 13 matching lines @@
   // Interface for dispatching events.
   std::unique_ptr<DeviceEventDispatcherEvdev> dispatcher_;
 
   DISALLOW_COPY_AND_ASSIGN(InputInjectorEvdev);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_OZONE_EVDEV_INPUT_INJECTOR_EVDEV_H_