AutoFill: Release the cached frame when we receive the frameDestroyed() message
from WebKit.

BUG=48857
TEST=none

Review URL: http://codereview.chromium.org/3173005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@55789 0039d316-1c4b-4281-b951-d872f2087c98
WebWidget* RenderView::createPopupMenu(WebKit::WebPopupType popup_type) {
  RenderWidget* widget = RenderWidget::Create(routing_id_,
                                              render_thread_,
                                              popup_type);
  return widget->webwidget();
}

WebWidget* RenderView::createPopupMenu(WebKit::WebPopupType popup_type) {
  RenderWidget* widget = RenderWidget::Create(routing_id_,
                                              render_thread_,
                                              popup_type);
  return widget->webwidget();
}
