Splits ToplevelWindowEventHandler into two

ash/wm/common/BUILD.gn

 # 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 import("//ui/base/ui_features.gni")
 
 assert(use_aura)
@@ skipping 63 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 33 matching lines @@
     "//ui/keyboard",
     "//ui/views",
     "//ui/wm",
   ]
 
   if (is_win) {
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
   }
 }