Add a PrinterDiscoverer fake object.

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 327 matching lines @@
       'network/portal_detector/network_portal_detector_strategy.cc',
       'network/portal_detector/network_portal_detector_strategy.h',
       'network/portal_detector/network_portal_detector_stub.cc',
       'network/portal_detector/network_portal_detector_stub.h',
       'network/prohibited_technologies_handler.cc',
       'network/prohibited_technologies_handler.h',
       'network/shill_property_handler.cc',
       'network/shill_property_handler.h',
       'network/shill_property_util.cc',
       'network/shill_property_util.h',
+      'printing/fake_printer_detector.cc',
+      'printing/fake_printer_detector.h',
       'printing/printer_configuration.cc',
       'printing/printer_configuration.h',
+      'printing/printer_detector.h',
       'printing/printer_translator.cc',
       'printing/printer_translator.h',
       'process_proxy/process_output_watcher.cc',
       'process_proxy/process_output_watcher.h',
       'process_proxy/process_proxy.cc',
       'process_proxy/process_proxy.h',
       'process_proxy/process_proxy_registry.cc',
       'process_proxy/process_proxy_registry.h',
       'settings/cros_settings_names.cc',
       'settings/cros_settings_names.h',
@@ skipping 366 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'chromeos_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }