Make PointerDeviceObserver use ui::InputDeviceEventObserver on X11

chrome/browser/chromeos/system/pointer_device_observer.h

 // Copyright (c) 2012 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 CHROME_BROWSER_CHROMEOS_SYSTEM_POINTER_DEVICE_OBSERVER_H_
 #define CHROME_BROWSER_CHROMEOS_SYSTEM_POINTER_DEVICE_OBSERVER_H_
 
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
-#include "chrome/browser/chromeos/device_hierarchy_observer.h"
 #include "ui/events/devices/input_device_event_observer.h"
 
 namespace chromeos {
 namespace system {
 
-class PointerDeviceObserver : public DeviceHierarchyObserver,
-                              public ui::InputDeviceEventObserver {
+class PointerDeviceObserver : public ui::InputDeviceEventObserver {
  public:
   PointerDeviceObserver();
   ~PointerDeviceObserver() override;
 
   // Start observing device hierarchy.
   void Init();
 
   // Check for presence of devices.
   void CheckDevices();
 
   class Observer {
    public:
     virtual void TouchpadExists(bool exists) = 0;
     virtual void MouseExists(bool exists) = 0;
 
    protected:
     Observer() {}
     virtual ~Observer();
   };
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
  private:
-  // DeviceHierarchyObserver:
-  void DeviceHierarchyChanged() override;
-  void DeviceAdded(int device_id) override {}
-  void DeviceRemoved(int device_id) override {}
-
   // InputDeviceEventObserver:
   void OnMouseDeviceConfigurationChanged() override;
   void OnTouchpadDeviceConfigurationChanged() override;
 
   // Check for pointer devices.
   void CheckTouchpadExists();
   void CheckMouseExists();
 
   // Callback for pointer device checks.
   void OnTouchpadExists(bool exists);
   void OnMouseExists(bool exists);
 
   ObserverList<Observer> observers_;
 
   base::WeakPtrFactory<PointerDeviceObserver> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PointerDeviceObserver);
 };
 
 }  // namespace system
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_SYSTEM_POINTER_DEVICE_OBSERVER_H_