Splits ToplevelWindowEventHandler into two

ash/wm/common/ash_wm_common.gyp

 # Copyright 2016 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.
 
 {
   'targets': [
     {
       'target_name': 'ash_wm_common',
       'type': '<(component)',
       'dependencies': [
@@ skipping 75 matching lines @@
         'wm_layout_manager.h',
         'wm_lookup.cc',
         'wm_lookup.h',
         'wm_overview_mode_observer.h',
         'wm_root_window_controller.h',
         'wm_root_window_controller_observer.h',
         'wm_screen_util.cc',
         'wm_screen_util.h',
         'wm_snap_to_pixel_layout_manager.cc',
         'wm_snap_to_pixel_layout_manager.h',
+        'wm_toplevel_window_event_handler.cc',
+        'wm_toplevel_window_event_handler.h',
         'wm_types.cc',
         'wm_types.h',
         'wm_user_metrics_action.h',
         'wm_window.h',
         'wm_window_observer.h',
         'wm_window_property.h',
         'wm_window_tracker.h',
         'workspace/magnetism_matcher.cc',
         'workspace/magnetism_matcher.h',
         'workspace/multi_window_resize_controller.cc',
@@ skipping 12 matching lines @@
       ],
       'conditions': [
         ['OS=="win"', {
           # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
           'msvs_disabled_warnings': [ 4267, ],
         }],
       ],
     },
   ],
 }