GTK: Fix a couple minor popup window icon menu bugs.

BUG=26265,26268

Review URL: http://codereview.chromium.org/360023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@31009 0039d316-1c4b-4281-b951-d872f2087c98
void MenuGtk::OnMenuShow(GtkWidget* widget, MenuGtk* menu) {
  MessageLoop::current()->PostTask(FROM_HERE,
      menu->factory_.NewRunnableMethod(&MenuGtk::UpdateMenu));
}

void MenuGtk::OnMenuShow(GtkWidget* widget, MenuGtk* menu) {
  MessageLoop::current()->PostTask(FROM_HERE,
      menu->factory_.NewRunnableMethod(&MenuGtk::UpdateMenu));
}
