ozone: evdev: Add gamepad support

ui/events/devices/input_device_event_observer.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_DEVICES_INPUT_DEVICE_EVENT_OBSERVER_H_
 #define UI_EVENTS_DEVICES_INPUT_DEVICE_EVENT_OBSERVER_H_
 
 #include "ui/events/devices/events_devices_export.h"
 
 namespace ui {
 
 enum class StylusState;
 
 // DeviceDataManager observer used to announce input hotplug events.
 class EVENTS_DEVICES_EXPORT InputDeviceEventObserver {
  public:
   virtual ~InputDeviceEventObserver() {}
 
   virtual void OnKeyboardDeviceConfigurationChanged() {}
   virtual void OnTouchscreenDeviceConfigurationChanged() {}
   virtual void OnMouseDeviceConfigurationChanged() {}
   virtual void OnTouchpadDeviceConfigurationChanged() {}
+  virtual void OnGamepadDeviceConfigurationChanged() {}
   virtual void OnDeviceListsComplete() {}
   virtual void OnStylusStateChanged(StylusState state) {}
 
  protected:
   InputDeviceEventObserver() {}
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_DEVICES_INPUT_DEVICE_EVENT_OBSERVER_H_