Add a 'cygwin' target to execute setup_mount.bat explicitly as a...

build/win/system.gyp

+# Copyright (c) 2009 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.
+
+{
+  'includes': [
+    '../common.gypi',
+  ],
+  'targets': [
+    {
+      'target_name': 'cygwin',
+      'type': 'none',
+      'actions': [
+        {
+          'action_name': 'setup_mount',
+          'inputs': [
+            '../../third_party/cygwin/setup_mount.bat',
+          ],
+          # Visual Studio requires an output file, or else the
+          # custom build step won't run.
+          'outputs': [
+            '../../third_party/cygwin/_always_run_setup_mount.marker',
+          ],
+          'action': ['<@(_inputs)'],
+        },
+      ],
+    },
+  ],
+}