Add media device attach notification mechanism.

base/base.gyp

 # Copyright (c) 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'includes': [
     '../build/win_precompile.gypi',
@@ skipping 391 matching lines @@
         ['os_bsd==1', {
           'sources!': [
             'test/test_file_util_linux.cc',
           ],
         }],
       ],
       'sources': [
         'perftimer.cc',
         'test/mock_chrome_application_mac.h',
         'test/mock_chrome_application_mac.mm',
+        'test/mock_devices_changed_observer.cc',
+        'test/mock_devices_changed_observer.h',
         'test/mock_time_provider.cc',
         'test/mock_time_provider.h',
         'test/multiprocess_test.cc',
         'test/multiprocess_test.h',
         'test/perf_test_suite.cc',
         'test/perf_test_suite.h',
         'test/scoped_locale.cc',
         'test/scoped_locale.h',
         'test/test_file_util.h',
         'test/test_file_util_linux.cc',
@@ skipping 121 matching lines @@
              # treated as weak imports in dependents, who still must
              # #include closure_blocks_leopard_compat.h to get weak imports.
              'type': 'none',
            }],
          ],
        },
      ],
    }],
   ],
 }