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
bool RenderView::runModalConfirmDialog(
    WebFrame* frame, const WebString& message) {
  return RunJavaScriptMessage(MessageBoxFlags::kIsJavascriptConfirm,
                              UTF16ToWideHack(message),
                              std::wstring(),
                              frame->url(),
                              NULL);
}

bool RenderView::runModalConfirmDialog(
    WebFrame* frame, const WebString& message) {
  return RunJavaScriptMessage(MessageBoxFlags::kIsJavascriptConfirm,
                              UTF16ToWideHack(message),
                              std::wstring(),
                              frame->url(),
                              NULL);
}
