mash: Move ShelfWindowTargeter out of shelf_widget.cc

ash/ash.gyp

 # 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': {
     'chromium_code': 1,
     # These files lists are shared with the GN build.
     'ash_sources': [
       'accelerators/accelerator_commands_aura.cc',
@@ skipping 633 matching lines @@
       'shelf/shelf_icon_observer.h',
       'shelf/shelf_layout_manager.cc',
       'shelf/shelf_layout_manager.h',
       'shelf/shelf_layout_manager_observer.h',
       'shelf/shelf_util.cc',
       'shelf/shelf_util.h',
       'shelf/shelf_view.cc',
       'shelf/shelf_view.h',
       'shelf/shelf_widget.cc',
       'shelf/shelf_widget.h',
+      'shelf/shelf_window_targeter.cc',
+      'shelf/shelf_window_targeter.h',
       'shell.cc',
       'shell.h',
       'shell_init_params.cc',
       'shell_init_params.h',
       'snap_to_pixel_layout_manager.cc',
       'snap_to_pixel_layout_manager.h',
       'sticky_keys/sticky_keys_controller.cc',
       'sticky_keys/sticky_keys_controller.h',
       'sticky_keys/sticky_keys_overlay.cc',
       'sticky_keys/sticky_keys_overlay.h',
@@ skipping 814 matching lines @@
                   '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
                 ],
               }
             ],
           ],
         },
       ],
     }],
   ],
 }