Add a mock class for DiskMountManagerObserver. disk_mount_manager_observer_unittests will be rewrit…

chromeos/chromeos.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,
     # These files lists are shared with the GN build.
     'chromeos_sources': [
       'accelerometer/accelerometer_reader.cc',
@@ skipping 446 matching lines @@
       'dbus/services/proxy_resolution_service_provider_unittest.cc',
       'dbus/shill_client_unittest_base.cc',
       'dbus/shill_client_unittest_base.h',
       'dbus/shill_device_client_unittest.cc',
       'dbus/shill_ipconfig_client_unittest.cc',
       'dbus/shill_manager_client_unittest.cc',
       'dbus/shill_profile_client_unittest.cc',
       'dbus/shill_service_client_unittest.cc',
       'dbus/shill_third_party_vpn_driver_client_unittest.cc',
       'disks/disk_mount_manager_unittest.cc',
+      'disks/mock_disk_mount_manager_observer.cc',
       'disks/suspend_unmount_manager_unittest.cc',
       'geolocation/simple_geolocation_unittest.cc',
       'login/auth/key_unittest.cc',
       'login/login_state_unittest.cc',
       'network/auto_connect_handler_unittest.cc',
       'network/client_cert_resolver_unittest.cc',
       'network/firewall_hole_unittest.cc',
       'network/geolocation_handler_unittest.cc',
       'network/host_resolver_impl_chromeos_unittest.cc',
       'network/managed_network_configuration_handler_unittest.cc',
@@ skipping 270 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'chromeos_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }