Make PointerDeviceObserver use ui::InputDeviceEventObserver on X11

chrome/browser/chromeos/system/pointer_device_observer.h

Index: chrome/browser/chromeos/system/pointer_device_observer.h
diff --git a/chrome/browser/chromeos/system/pointer_device_observer.h b/chrome/browser/chromeos/system/pointer_device_observer.h
index 1415c449e2b3f1626c765172437415376f15cf40..c813da49bffb9686428ca20907ab644b32a8a308 100644
--- a/chrome/browser/chromeos/system/pointer_device_observer.h
+++ b/chrome/browser/chromeos/system/pointer_device_observer.h
@@ -7,14 +7,12 @@
 
 #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;
@@ -38,11 +36,6 @@ class PointerDeviceObserver : public DeviceHierarchyObserver,
   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;