gtk: Add dummy implementation of dialog.

browser/ui/message_box_gtk.cc

@@ -0,0 +1,30 @@
+// Copyright (c) 2014 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/ui/message_box.h"
+
+#include "base/callback.h"
+
+namespace atom {
+
+int ShowMessageBox(NativeWindow* parent_window,
+                   MessageBoxType type,
+                   const std::vector<std::string>& buttons,
+                   const std::string& title,
+                   const std::string& message,
+                   const std::string& detail) {
+  return 0;
+}
+
+void ShowMessageBox(NativeWindow* parent_window,
+                    MessageBoxType type,
+                    const std::vector<std::string>& buttons,
+                    const std::string& title,
+                    const std::string& message,
+                    const std::string& detail,
+                    const MessageBoxCallback& callback) {
+  callback.Run(0);
+}
+
+}  // namespace atom