Enforce WARN_UNUSED_RESULT attribute on Windows

components/storage_monitor.gypi

 # 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.
 
 {
   'targets': [
     {
       # GN version: //components/storage_monitor
       'target_name': 'storage_monitor',
       'type': 'static_library',
@@ skipping 103 matching lines @@
         'storage_monitor/test_volume_mount_watcher_win.h',
       ],
       'conditions': [
         ['OS=="linux"', {
           'dependencies': [
             '../device/media_transfer_protocol/media_transfer_protocol.gyp:device_media_transfer_protocol',
             '../device/media_transfer_protocol/media_transfer_protocol.gyp:mtp_file_entry_proto',
             '../device/media_transfer_protocol/media_transfer_protocol.gyp:mtp_storage_info_proto',
           ],
         }],
+        ['OS=="win"', {
+          'dependencies': [
+            '../testing/gtest.gyp:gtest',
+          ],
+        }],
       ],
     },
   ],
 }