Version: v5.0.5, v5.0.6
JavaScript code: `document.querySelector('iframe').contentWindow.print()`
shell/browser/api/atom_api_web_contents.cc
mate::Arguments* args) {
  base::FilePath file;
  std::vector<base::FilePath> files;
  if (!item.Get("files", &files) && item.Get("file", &file)) {
    files.push_back(file);
  }
  mate::Handle<NativeImage> icon;
  if (!item.Get("icon", &icon) && !file.empty()) {
    
  }
  
  if (icon.IsEmpty()) {
    args->ThrowError("Must specify 'icon' option");
    return;
  }
#if defined(OS_MACOSX)
  
  if (icon->image().IsEmpty()) {
    args->ThrowError("Must specify non-empty 'icon' option");
    return;
  }
#endif
  
  if (!files.empty()) {
    base::MessageLoopCurrent::ScopedNestableTaskAllower allow;
    DragFileItems(files, icon->image(), web_contents()->GetNativeView());
  } else {
    args->ThrowError("Must specify either 'file' or 'files' option");
  }