Move UserActivityDetector to ui/base/user_activity/.

ui/wm/wm.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 63 matching lines @@
         'core/shadow_controller.h',
         'core/shadow_types.cc',
         'core/shadow_types.h',
         'core/transient_window_controller.cc',
         'core/transient_window_controller.h',
         'core/transient_window_manager.cc',
         'core/transient_window_manager.h',
         'core/transient_window_observer.h',
         'core/transient_window_stacking_client.cc',
         'core/transient_window_stacking_client.h',
-        'core/user_activity_detector.cc',
-        'core/user_activity_detector.h',
-        'core/user_activity_observer.h',
         'core/visibility_controller.cc',
         'core/visibility_controller.h',
         'core/window_animations.cc',
         'core/window_animations.h',
         'core/window_modality_controller.cc',
         'core/window_modality_controller.h',
         'core/window_util.cc',
         'core/window_util.h',
         'core/wm_core_switches.cc',
         'core/wm_core_switches.h',
@@ skipping 44 matching lines @@
         'core/compound_event_filter_unittest.cc',
         'core/cursor_manager_unittest.cc',
         'core/focus_controller_unittest.cc',
         'core/input_method_event_filter_unittest.cc',
         'core/image_grid_unittest.cc',
         'core/nested_accelerator_controller_unittest.cc',
         'core/shadow_controller_unittest.cc',
         'core/shadow_unittest.cc',
         'core/transient_window_manager_unittest.cc',
         'core/transient_window_stacking_client_unittest.cc',
-        'core/user_activity_detector_unittest.cc',
         'core/visibility_controller_unittest.cc',
         'core/window_animations_unittest.cc',
         'core/window_util_unittest.cc',
       ],
     },
   ],
 }