Make PointerDeviceObserver use ui::InputDeviceEventObserver on X11

chrome/chrome_browser_chromeos.gypi

 # 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.
 
 {
   'variables': {
     # These files lists are shared with the GN build.
     'browser_chromeos_sources': [
         # All .cc, .h, .m, and .mm files under browser/chromeos, except for tests
@@ skipping 67 matching lines @@
         'browser/chromeos/dbus/chrome_display_power_service_provider_delegate.cc',
         'browser/chromeos/dbus/chrome_display_power_service_provider_delegate.h',
         'browser/chromeos/dbus/chrome_proxy_resolver_delegate.cc',
         'browser/chromeos/dbus/chrome_proxy_resolver_delegate.h',
         'browser/chromeos/dbus/printer_service_provider.cc',
         'browser/chromeos/dbus/printer_service_provider.h',
         'browser/chromeos/dbus/screen_lock_service_provider.cc',
         'browser/chromeos/dbus/screen_lock_service_provider.h',
         'browser/chromeos/device/input_service_proxy.cc',
         'browser/chromeos/device/input_service_proxy.h',
-        'browser/chromeos/device_hierarchy_observer.h',
         'browser/chromeos/device_uma.cc',
         'browser/chromeos/device_uma.h',
         'browser/chromeos/display/display_configuration_observer.cc',
         'browser/chromeos/display/display_configuration_observer.h',
         'browser/chromeos/display/display_preferences.cc',
         'browser/chromeos/display/display_preferences.h',
         'browser/chromeos/display/overscan_calibrator.cc',
         'browser/chromeos/display/overscan_calibrator.h',
         'browser/chromeos/drive/change_list_loader.cc',
         'browser/chromeos/drive/change_list_loader.h',
@@ skipping 1195 matching lines @@
         'browser/chromeos/attestation/attestation_signed_data.proto',
       ],
       'variables': {
         'proto_in_dir': 'browser/chromeos/attestation',
         'proto_out_dir': 'chrome/browser/chromeos/attestation',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],
 }