Add support for PNG representation in gfx::Image

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 344 matching lines @@
         'gfx/font_render_params_linux.cc',
         'gfx/font_render_params_linux.h',
         'gfx/font_smoothing_win.cc',
         'gfx/font_smoothing_win.h',
         'gfx/gfx_paths.cc',
         'gfx/gfx_paths.h',
         'gfx/image/canvas_image_source.cc',
         'gfx/image/canvas_image_source.h',
         'gfx/image/image.cc',
         'gfx/image/image.h',
+        'gfx/image/image_mac.mm',
         'gfx/image/image_skia.cc',
         'gfx/image/image_skia.h',
         'gfx/image/image_skia_operations.cc',
         'gfx/image/image_skia_operations.h',
         'gfx/image/image_skia_rep.cc',
         'gfx/image/image_skia_rep.h',
         'gfx/image/image_skia_source.h',
         'gfx/image/image_skia_util_mac.h',
         'gfx/image/image_skia_util_mac.mm',
         'gfx/image/image_util.cc',
@@ skipping 380 matching lines @@
                 'shutil.copyfile(\'<(ui_copy_target)\', \'<(ui_copy_dest)\'); ' \
                 'os.chmod(\'<(ui_copy_dest)\', 0700)'
               ]
             }
           ],
         },
       ],
     }],
   ],
 }