Add update observer to file_system_operation_impl_unittest for

content/content_tests.gypi

 # Copyright (c) 2013 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': {
     'layouttest_support_content_sources': [
       'public/test/layouttest_support.h',
       'public/test/nested_message_pump_android.cc',
       'public/test/nested_message_pump_android.h',
@@ skipping 434 matching lines @@
         'browser/fileapi/file_system_url_unittest.cc',
         'browser/fileapi/file_system_usage_cache_unittest.cc',
         'browser/fileapi/file_writer_delegate_unittest.cc',
         'browser/fileapi/fileapi_message_filter_unittest.cc',
         'browser/fileapi/isolated_context_unittest.cc',
         'browser/fileapi/local_file_stream_reader_unittest.cc',
         'browser/fileapi/local_file_stream_writer_unittest.cc',
         'browser/fileapi/local_file_util_unittest.cc',
         'browser/fileapi/mock_file_change_observer.cc',
         'browser/fileapi/mock_file_change_observer.h',
+        'browser/fileapi/mock_file_update_observer.cc',
+        'browser/fileapi/mock_file_update_observer.h',
         'browser/fileapi/mock_url_request_delegate.cc',
         'browser/fileapi/mock_url_request_delegate.h',
         'browser/fileapi/native_file_util_unittest.cc',
         'browser/fileapi/obfuscated_file_util_unittest.cc',
         'browser/fileapi/plugin_private_file_system_backend_unittest.cc',
         'browser/fileapi/recursive_operation_delegate_unittest.cc',
         'browser/fileapi/sandbox_database_test_helper.cc',
         'browser/fileapi/sandbox_database_test_helper.h',
         'browser/fileapi/sandbox_directory_database_unittest.cc',
         'browser/fileapi/sandbox_file_system_backend_delegate_unittest.cc',
@@ skipping 1424 matching lines @@
                   'files': ['<(PRODUCT_DIR)/libnpapi_test_plugin.so'],
                 },
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }