Added UMA statistics for changing the active window via click or touch events.

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 66 matching lines @@
         '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/visibility_controller.cc',
         'core/visibility_controller.h',
+        'core/window_activation_pre_target_handler.cc',
+        'core/window_activation_pre_target_handler.h',
+        'core/window_activation_pre_target_handler_observer.cc',
+        'core/window_activation_pre_target_handler_observer.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',
         'core/wm_state.cc',
         'core/wm_state.h',
@@ skipping 57 matching lines @@
         'core/transient_window_manager_unittest.cc',
         'core/transient_window_stacking_client_unittest.cc',
         'core/visibility_controller_unittest.cc',
         'core/window_animations_unittest.cc',
         'core/window_util_unittest.cc',
         'test/run_all_unittests.cc',
       ],
     },
   ],
 }