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 352 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 @@
   ],
   'conditions': [
     ['inside_chromium_build == 1 and OS != "ios"', {
       # TODO(ios): The ui tests do not compile yet on iOS.
       'includes': [
         'ui_unittests.gypi',
       ]},
     ],
   ],
 }