Introduces a new scrollbar for message_center.

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,
   },
   'target_defaults': {
     'conditions': [
       ['use_aura==1', {
@@ skipping 170 matching lines @@
         'controls/scrollbar/base_scroll_bar_thumb.h',
         'controls/scrollbar/bitmap_scroll_bar.cc',
         'controls/scrollbar/bitmap_scroll_bar.h',
         'controls/scrollbar/kennedy_scroll_bar.cc',
         'controls/scrollbar/kennedy_scroll_bar.h',
         'controls/scrollbar/native_scroll_bar_views.cc',
         'controls/scrollbar/native_scroll_bar_views.h',
         'controls/scrollbar/native_scroll_bar_wrapper.h',
         'controls/scrollbar/native_scroll_bar.cc',
         'controls/scrollbar/native_scroll_bar.h',
+        'controls/scrollbar/overlay_scroll_bar.cc',
+        'controls/scrollbar/overlay_scroll_bar.h',
         'controls/scrollbar/scroll_bar.cc',
         'controls/scrollbar/scroll_bar.h',
         'controls/separator.cc',
         'controls/separator.h',
         'controls/single_split_view.cc',
         'controls/single_split_view.h',
         'controls/single_split_view_listener.h',
         'controls/slide_out_view.cc',
         'controls/slide_out_view.h',
         'controls/slider.cc',
@@ skipping 813 matching lines @@
           'sources/': [
             # This is needed because the aura rule strips it from the default
             # sources list.
             ['include', '^../../content/app/startup_helper_win.cc'],
           ],
         }],
       ],
     },  # target_name: views_examples_with_content_exe
   ],
 }