Move nsimage_cache into base so that it can be accessed from outside of chrome

base/base.gyp

 # Copyright (c) 2009 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 178 matching lines @@
         'message_pump_win.cc',
         'message_pump_win.h',
         'mime_util.h',
         'mime_util_linux.cc',
         'native_library.h',
         'native_library_linux.cc',
         'native_library_mac.mm',
         'native_library_win.cc',
         'non_thread_safe.cc',
         'non_thread_safe.h',
+        'nsimage_cache_mac.h',
+        'nsimage_cache_mac.mm',
         'nss_init.cc',
         'nss_init.h',
         'nullable_string16.h',
         'object_watcher.cc',
         'object_watcher.h',
         'observer_list.h',
         'observer_list_threadsafe.h',
         'path_service.cc',
         'path_service.h',
         'pe_image.cc',
@@ skipping 637 matching lines @@
                 '<@(_outputs)',
               ],
               'message': 'Generating version information',
             },
           ],
         },
       ],
     }],
   ],
 }