Add dummy implementation of file dialog for Windows.

atom.gyp

@@ -90,6 +90,7 @@
       'browser/crash_reporter_win.cc',
       'browser/file_dialog.h',
       'browser/file_dialog_mac.mm',
+      'browser/file_dialog_win.cc',
       'browser/media/media_capture_devices_dispatcher.cc',
       'browser/media/media_capture_devices_dispatcher.h',
       'browser/media/media_stream_devices_controller.cc',

browser/file_dialog_win.cc

@@ -0,0 +1,23 @@
+// Copyright (c) 2013 GitHub, Inc. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "browser/file_dialog.h"
+
+namespace file_dialog {
+
+bool ShowOpenDialog(const std::string& title,
+                    const base::FilePath& default_path,
+                    int properties,
+                    std::vector<base::FilePath>* paths) {
+  return false;
+}
+
+bool ShowSaveDialog(atom::NativeWindow* window,
+                    const std::string& title,
+                    const base::FilePath& default_path,
+                    base::FilePath* path) {
+  return false;
+}
+
+}  // namespace file_dialog