During upgrade to the Chromium 61 we have switched from GTK2 to GTK3
and now we have a few warnings about stuff being deprecated in GTK3.
Check any Linux build to get a list of them.

/cc @zcbenz 
atom/browser/ui/file_dialog_gtk.cc
for (size_t i = 0; i < filters.size(); ++i) {
    const Filter& filter = filters[i];
    GtkFileFilter* gtk_filter = gtk_file_filter_new();
    for (size_t j = 0; j < filter.second.size(); ++j) {
      std::unique_ptr<std::string> file_extension(
          new std::string("." + filter.second[j]));
      gtk_file_filter_add_custom(
          gtk_filter,
          GTK_FILE_FILTER_FILENAME,
          reinterpret_cast<GtkFileFilterFunc>(FileFilterCaseInsensitive),
          file_extension.release(),
          reinterpret_cast<GDestroyNotify>(OnFileFilterDataDestroyed));
    }
    gtk_file_filter_set_name(gtk_filter, filter.first.c_str());
    gtk_file_chooser_add_filter(GTK_FILE_CHOOSER(dialog_), gtk_filter);
  }
}
base::FilePath FileChooserDialog::AddExtensionForFilename(