Add FakeClipboard implementation for unit 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 687 matching lines @@
       'target_name': 'ui_base_test_support',
       'dependencies': [
         '../../base/base.gyp:base',
         '../../skia/skia.gyp:skia',
         '../../testing/gtest.gyp:gtest',
         '../gfx/gfx.gyp:gfx',
         '../gfx/gfx.gyp:gfx_geometry',
       ],
       'sources': [
         # Note: file list duplicated in GN build.
+        'test/test_clipboard.cc',
+        'test/test_clipboard.h',
         'test/ui_controls.h',
         'test/ui_controls_aura.cc',
         'test/ui_controls_internal_win.cc',
         'test/ui_controls_internal_win.h',
         'test/ui_controls_mac.mm',
         'test/ui_controls_win.cc',
       ],
       'include_dirs': [
         '../..',
       ],
@@ skipping 43 matching lines @@
            ],
            'variables': {
              'jni_gen_package': 'ui',
            },
            'includes': [ '../../build/jni_generator.gypi' ],
          },
        ],
     }],
   ],
 }