[MacViews] Enable dragging a window by its caption/draggable areas.

ui/views/views.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,
     # Sources lists shared with GN build.
     'views_sources': [
       'accessibility/native_view_accessibility.cc',
       'accessibility/native_view_accessibility.h',
@@ skipping 18 matching lines @@
       'button_drag_utils.cc',
       'button_drag_utils.h',
       'cocoa/bridged_content_view.h',
       'cocoa/bridged_content_view.mm',
       'cocoa/bridged_native_widget.h',
       'cocoa/bridged_native_widget.mm',
       'cocoa/bridged_native_widget_owner.h',
       'cocoa/cocoa_mouse_capture.h',
       'cocoa/cocoa_mouse_capture.mm',
       'cocoa/cocoa_mouse_capture_delegate.h',
+      'cocoa/cocoa_non_client_drag.h',
+      'cocoa/cocoa_non_client_drag.mm',
       'cocoa/native_widget_mac_nswindow.h',
       'cocoa/native_widget_mac_nswindow.mm',
       'cocoa/views_nswindow_delegate.h',
       'cocoa/views_nswindow_delegate.mm',
       'cocoa/widget_owner_nswindow_adapter.h',
       'cocoa/widget_owner_nswindow_adapter.mm',
       'color_chooser/color_chooser_listener.h',
       'color_chooser/color_chooser_view.cc',
       'color_chooser/color_chooser_view.h',
       'color_constants.cc',
@@ skipping 878 matching lines @@
                 '../aura/aura.gyp:aura',
                 '../wm/wm.gyp:wm',
               ],
             }],
           ],
         },  # target_name: macviews_interactive_ui_tests
       ],  # targets
     }],
   ],  # conditions
 }