Implement clipboard for aura and re-enable clipboard_unittests.

ui/ui_unittests.gypi

 # Copyright (c) 2011 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.
 
 {
   'targets': [
     {
       'target_name': 'ui_test_support',
       'dependencies': [
         '../base/base.gyp:base',
@@ skipping 152 matching lines @@
           ],
           'dependencies': [
             '../build/linux/system.gyp:gtk',
           ],
         }],
         ['toolkit_views==1', {
           'sources': [
             'gfx/render_text_unittest.cc',
           ],
         }],
-        ['use_aura==1 and OS!="win"', {
-          'sources!': [
-            # aura does not yet have clipboard support. http://crbug.com/97845
-            'base/clipboard/clipboard_unittest.cc',
-          ],
-        }],
       ],
     },
   ],
 }