Views: factor out Combobox background and const-ify style

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 260 matching lines @@
         'platform_font_mac.h',
         'platform_font_mac.mm',
         'platform_font_win.cc',
         'platform_font_win.h',
         'render_text.cc',
         'render_text.h',
         'render_text_harfbuzz.cc',
         'render_text_harfbuzz.h',
         'render_text_mac.h',
         'render_text_mac.mm',
+        'scoped_canvas.cc',
         'scoped_canvas.h',
         'scoped_cg_context_save_gstate_mac.h',
         'scoped_ns_graphics_context_save_gstate_mac.h',
         'scoped_ns_graphics_context_save_gstate_mac.mm',
         'scoped_ui_graphics_push_context_ios.h',
         'scoped_ui_graphics_push_context_ios.mm',
         'scrollbar_size.cc',
         'scrollbar_size.h',
         'selection_model.cc',
         'selection_model.h',
@@ skipping 289 matching lines @@
          ],
          'variables': {
            'jni_gen_package': 'ui/gfx',
          },
          'includes': [ '../../build/jni_generator.gypi' ],
        },
      ],
     }],
   ],
 }