Add CdmService to keep track of CDMs

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 662 matching lines @@
       'common/host_shared_bitmap_manager_unittest.cc',
       'common/id_type_unittest.cc',
       'common/indexed_db/indexed_db_key_unittest.cc',
       'common/input/gesture_event_stream_validator_unittest.cc',
       'common/input/input_param_traits_unittest.cc',
       'common/input/touch_event_stream_validator_unittest.cc',
       'common/input/web_input_event_traits_unittest.cc',
       'common/inter_process_time_ticks_converter_unittest.cc',
       'common/mac/attributed_string_coder_unittest.mm',
       'common/mac/font_descriptor_unittest.mm',
+      'common/media/key_system_service_unittest.cc',
       'common/one_writer_seqlock_unittest.cc',
       'common/origin_util_unittest.cc',
       'common/page_state_serialization_unittest.cc',
       'common/page_zoom_unittest.cc',
       'common/plugin_list_unittest.cc',
       'common/sandbox_mac_compiler_unittest.mm',
       'common/sandbox_mac_diraccess_unittest.mm',
       'common/sandbox_mac_fontloading_unittest.mm',
       'common/sandbox_mac_system_access_unittest.mm',
       'common/sandbox_mac_unittest_helper.h',
@@ skipping 1522 matching lines @@
                   'content_unittests_apk.isolate',
                 ],
               },
             ],
           },
         ],
       ],
     }],
   ],
 }