ash: Convert ShelfDelegate to use WmShelf* instead of Shelf*

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 892 matching lines @@
     'ash_shell_lib_sources': [
       '../ui/views/test/test_views_delegate_aura.cc',
       'shell/app_list.cc',
       'shell/bubble.cc',
       'shell/context_menu.cc',
       'shell/context_menu.h',
       'shell/example_factory.h',
       'shell/lock_view.cc',
       'shell/panel_window.cc',
       'shell/panel_window.h',
-      'shell/shelf_delegate_impl.cc',
-      'shell/shelf_delegate_impl.h',
       'shell/shell_delegate_impl.cc',
       'shell/shell_delegate_impl.h',
       'shell/toplevel_window.cc',
       'shell/toplevel_window.h',
       'shell/widgets.cc',
       'shell/window_type_launcher.cc',
       'shell/window_type_launcher.h',
       'shell/window_watcher.cc',
       'shell/window_watcher.h',
       'shell/window_watcher_shelf_item_delegate.cc',
@@ skipping 586 matching lines @@
                   '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
                 ],
               }
             ],
           ],
         },
       ],
     }],
   ],
 }