Add browser_tests to the GN build.

device/serial/serial.gyp

 # Copyright 2014 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,
   },
   'targets': [
     {
@@ skipping 73 matching lines @@
         'serial_io_handler.h',
         'serial_io_handler_posix.cc',
         'serial_io_handler_posix.h',
         'serial_io_handler_win.cc',
         'serial_io_handler_win.h',
         'serial_service_impl.cc',
         'serial_service_impl.h',
       ],
     },
     {
-      # GN version: //device/serial:test_util
+      # GN version: //device/serial:test_support
       'target_name': 'device_serial_test_util',
       'type': 'static_library',
       'dependencies': [
         'device_serial',
         'device_serial_mojo',
       ],
       'sources': [
         'test_serial_io_handler.cc',
         'test_serial_io_handler.h',
       ],
     },
   ],
 }