MacViews: Add native drop shadow to dialogs on OSX < 10.10.

ui/gfx/gfx.gyp

 # Copyright (c) 2013 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,
   },
   'targets': [
     {
@@ skipping 213 matching lines @@
         'mac/scoped_cocoa_disable_screen_updates.h',
         'native_pixmap_handle_ozone.h',
         'native_widget_types.h',
         'nine_image_painter.cc',
         'nine_image_painter.h',
         'overlay_transform.h',
         'paint_throbber.cc',
         'paint_throbber.h',
         'path.cc',
         'path.h',
+        'path_mac.h',
+        'path_mac.mm',
         'path_win.cc',
         'path_win.h',
         'path_x11.cc',
         'path_x11.h',
         'platform_font.h',
         'platform_font_android.cc',
         'platform_font_ios.h',
         'platform_font_ios.mm',
         'platform_font_linux.cc',
         'platform_font_linux.h',
@@ skipping 328 matching lines @@
          ],
          'variables': {
            'jni_gen_package': 'ui/gfx',
          },
          'includes': [ '../../build/jni_generator.gypi' ],
        },
      ],
     }],
   ],
 }