Per discussion, implement the Omaha Client Update Protocol (CUP) in src/crypto.

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 1750 matching lines @@
         '../components/autofill/browser/webdata/autofill_entry_unittest.cc',
         '../components/autofill/browser/webdata/autofill_table_unittest.cc',
         '../components/autofill/browser/webdata/web_data_service_unittest.cc',
         '../components/webdata/common/web_database_migration_unittest.cc',
         '../components/webdata/common/web_data_service_test_util.cc',
         '../components/webdata/common/web_data_service_test_util.h',
 
         # TODO(joi): Move the google_apis tests to a separate
         # google_apis_unittests executable.
         '../google_apis/google_api_keys_unittest.cc',
+        '../google_apis/cup/client_update_protocol_unittest.cc',
         '../google_apis/gaia/mock_url_fetcher_factory.h',
         '../google_apis/gaia/gaia_auth_fetcher_unittest.cc',
         '../google_apis/gaia/gaia_auth_util_unittest.cc',
         '../google_apis/gaia/gaia_authenticator_unittest.cc',
         '../google_apis/gaia/gaia_oauth_client_unittest.cc',
         '../google_apis/gaia/google_service_auth_error_unittest.cc',
         '../google_apis/gaia/oauth_request_signer_unittest.cc',
         '../google_apis/gaia/oauth2_access_token_fetcher_unittest.cc',
         '../google_apis/gaia/oauth2_api_call_flow_unittest.cc',
         '../google_apis/gaia/oauth2_mint_token_flow_unittest.cc',
@@ skipping 736 matching lines @@
               # more details.
               'DebugInformationFormat': '3',
               'ProgramDataBaseFileName': '<(PRODUCT_DIR)/unit_tests.exe.pdb',
             },
           },
         },
       ],
     }],
   ],  # 'conditions'
 }