CustomButton cleanup: make protected members private, create accessors

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 152 matching lines @@
       'controls/resize_area.h',
       'controls/resize_area_delegate.h',
       'controls/scroll_view.cc',
       'controls/scroll_view.h',
       'controls/scrollbar/base_scroll_bar.cc',
       'controls/scrollbar/base_scroll_bar.h',
       'controls/scrollbar/base_scroll_bar_button.cc',
       'controls/scrollbar/base_scroll_bar_button.h',
       'controls/scrollbar/base_scroll_bar_thumb.cc',
       'controls/scrollbar/base_scroll_bar_thumb.h',
-      'controls/scrollbar/kennedy_scroll_bar.cc',
-      'controls/scrollbar/kennedy_scroll_bar.h',
       'controls/scrollbar/native_scroll_bar.cc',
       'controls/scrollbar/native_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/overlay_scroll_bar.cc',
       'controls/scrollbar/overlay_scroll_bar.h',
       'controls/scrollbar/scroll_bar.cc',
       'controls/scrollbar/scroll_bar.h',
       'controls/separator.cc',
@@ skipping 788 matching lines @@
                 '../aura/aura.gyp:aura',
                 '../wm/wm.gyp:wm',
               ],
             }],
           ],
         },  # target_name: macviews_interactive_ui_tests
       ],  # targets
     }],
   ],  # conditions
 }