Add new NSPasteboard utility function and tests.

ui/base/ui_base.gyp

 # Copyright 2014 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 94 matching lines @@
         'clipboard/clipboard_android.cc',
         'clipboard/clipboard_android.h',
         'clipboard/clipboard_aura.cc',
         'clipboard/clipboard_aura.h',
         'clipboard/clipboard_aurax11.cc',
         'clipboard/clipboard_aurax11.h',
         'clipboard/clipboard_constants.cc',
         'clipboard/clipboard_mac.h',
         'clipboard/clipboard_mac.mm',
         'clipboard/clipboard_types.h',
+        'clipboard/clipboard_util_mac.h',
+        'clipboard/clipboard_util_mac.mm',
         'clipboard/clipboard_util_win.cc',
         'clipboard/clipboard_util_win.h',
         'clipboard/clipboard_win.cc',
         'clipboard/clipboard_win.h',
         'clipboard/custom_data_helper.cc',
         'clipboard/custom_data_helper.h',
         'clipboard/custom_data_helper_linux.cc',
         'clipboard/custom_data_helper_mac.mm',
         'clipboard/scoped_clipboard_writer.cc',
         'clipboard/scoped_clipboard_writer.h',
@@ skipping 649 matching lines @@
            ],
            'variables': {
              'jni_gen_package': 'ui',
            },
            'includes': [ '../../build/jni_generator.gypi' ],
          },
        ],
     }],
   ],
 }