Add code to compute the root hash for a hash tree

chrome/chrome_tests_unit.gypi

 # Copyright 2012 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': [
     {
       # This target contains mocks and test utilities that don't belong in
       # production libraries but are used by more than one test executable.
       'target_name': 'test_support_common',
       'type': 'static_library',
@@ skipping 513 matching lines @@
         # TODO(tfarina): Move these entries over to extensions_unittests target.
         # http://crbug.com/348066. They are duplicated here because we haven't
         # extensions_unittests running in the bots yet. Until that happens,
         # they should be kept here.
         '../extensions/browser/admin_policy_unittest.cc',
         '../extensions/browser/api/storage/settings_quota_unittest.cc',
         '../extensions/browser/api/storage/settings_test_util.cc',
         '../extensions/browser/api/storage/settings_test_util.h',
         '../extensions/browser/api/storage/storage_api_unittest.cc',
         '../extensions/browser/api/storage/storage_frontend_unittest.cc',
+        '../extensions/browser/content_hash_tree_unittest.cc',
         '../extensions/browser/error_map_unittest.cc',
         '../extensions/browser/event_listener_map_unittest.cc',
         '../extensions/browser/event_router_unittest.cc',
         '../extensions/browser/extension_error_test_util.cc',
         '../extensions/browser/extension_error_test_util.h',
         '../extensions/browser/extension_pref_value_map_unittest.cc',
         '../extensions/browser/extension_protocols_unittest.cc',
         '../extensions/browser/extension_registry_unittest.cc',
         '../extensions/browser/file_highlighter_unittest.cc',
         '../extensions/browser/file_reader_unittest.cc',
@@ skipping 2298 matching lines @@
               # more details.
               'DebugInformationFormat': '3',
               'ProgramDataBaseFileName': '<(PRODUCT_DIR)/unit_tests.exe.pdb',
             },
           },
         },
       ],
     }],
   ],  # 'conditions'
 }