Extract the code of showing a dragging window on another display from PhantomWindowController.

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,
     'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/chrome',
   },
   'includes': [
@@ skipping 280 matching lines @@
         'wm/coordinate_conversion.cc',
         'wm/coordinate_conversion.h',
         'wm/cursor_manager.cc',
         'wm/cursor_manager.h',
         'wm/custom_frame_view_ash.cc',
         'wm/custom_frame_view_ash.h',
         'wm/default_window_resizer.cc',
         'wm/default_window_resizer.h',
         'wm/dialog_frame_view.cc',
         'wm/dialog_frame_view.h',
+        'wm/drag_window_controller.cc',
+        'wm/drag_window_controller.h',
         'wm/event_client_impl.cc',
         'wm/event_client_impl.h',
         'wm/event_rewriter_event_filter.cc',
         'wm/event_rewriter_event_filter.h',
         'wm/frame_painter.cc',
         'wm/frame_painter.h',
         'wm/gestures/bezel_gesture_handler.cc',
         'wm/gestures/bezel_gesture_handler.h',
         'wm/gestures/long_press_affordance_handler.cc',
         'wm/gestures/long_press_affordance_handler.h',
@@ skipping 399 matching lines @@
             'shell/cocoa/app-Info.plist',
           ],
           'xcode_settings': {
             'INFOPLIST_FILE': 'shell/cocoa/app-Info.plist',
           },
         }],
       ],
     },
   ],
 }