mac: Delete GetCachedImageWithName(), it's no longer used.

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': [
     'shell_dialogs.gypi',
@@ skipping 387 matching lines @@
         'gfx/image/image_util.cc',
         'gfx/image/image_util.h',
         'gfx/image/image_util_ios.mm',
         'gfx/insets.cc',
         'gfx/insets.h',
         'gfx/insets_base.h',
         'gfx/insets_f.cc',
         'gfx/insets_f.h',
         'gfx/interpolated_transform.cc',
         'gfx/interpolated_transform.h',
-        'gfx/mac/nsimage_cache.h',
-        'gfx/mac/nsimage_cache.mm',
         'gfx/mac/scoped_ns_disable_screen_updates.h',
         'gfx/native_widget_types.h',
         'gfx/pango_util.cc',
         'gfx/pango_util.h',
         'gfx/path.cc',
         'gfx/path.h',
         'gfx/path_aura.cc',
         'gfx/path_gtk.cc',
         'gfx/path_win.cc',
         'gfx/path_win.h',
@@ skipping 506 matching lines @@
           'link_settings': {
             'libraries': [
               '$(SDKROOT)/System/Library/Frameworks/Cocoa.framework',
             ],
           },
         },
       ],
     }],
   ],
 }