evdev: Fix infinite loop when devices are unplugged

ui/events/ozone/evdev/event_factory.h

 // Copyright 2013 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_EVENT_FACTORY_DELEGATE_EVDEV_H_
 #define UI_EVENTS_OZONE_EVENT_FACTORY_DELEGATE_EVDEV_H_
 
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "ui/events/events_export.h"
 #include "ui/events/ozone/evdev/event_modifiers.h"
 #include "ui/events/ozone/event_factory_ozone.h"
 
 namespace ui {
 
+class EventConverterEvdev;
+
 // Ozone events implementation for the Linux input subsystem ("evdev").
 class EVENTS_EXPORT EventFactoryEvdev : public EventFactoryOzone {
  public:
   EventFactoryEvdev();
   virtual ~EventFactoryEvdev();
 
   virtual void StartProcessingEvents() OVERRIDE;
 
  private:
   // Open device at path & starting processing events.
   void AttachInputDevice(const base::FilePath& file_path);
 
   EventModifiersEvdev modifiers_;
 
   DISALLOW_COPY_AND_ASSIGN(EventFactoryEvdev);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_OZONE_EVENT_FACTORY_DELEGATE_EVDEV_H_