ui/gfx: Make gfx::Canvas inherit from gfx::CanvasSkia.

ui/ui.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,
   },
   'includes': [
     'ui_resources.gypi',
@@ skipping 224 matching lines @@
         'base/x/root_window_property_watcher_x.h',
         'base/x/work_area_watcher_x.cc',
         'base/x/work_area_watcher_x.h',
         'base/x/work_area_watcher_x_observer.h',
         'base/x/x11_util.cc',
         'base/x/x11_util.h',
         'base/x/x11_util_internal.h',
         'gfx/blit.cc',
         'gfx/blit.h',
         'gfx/brush.h',
-        'gfx/canvas.cc',
         'gfx/canvas.h',
         'gfx/canvas_paint.h',
         'gfx/canvas_paint_win.cc',
         'gfx/canvas_skia.h',
         'gfx/canvas_skia.cc',
         'gfx/canvas_skia_android.cc',
         'gfx/canvas_skia_linux.cc',
         'gfx/canvas_skia_mac.mm',
         'gfx/canvas_skia_paint.h',
         'gfx/canvas_skia_skia.cc',
@@ skipping 425 matching lines @@
                 'shutil.copyfile(\'<(ui_copy_target)\', \'<(ui_copy_dest)\'); ' \
                 'os.chmod(\'<(ui_copy_dest)\', 0700)'
               ]
             }
           ],
         },
       ],
     }],
   ],
 }