Don't populate URL data in WebDropData when dragging files.

This is considered a potential security issue as well, since it leaks
filesystem paths.

BUG=332579

Review URL: https://codereview.chromium.org/135633002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244538 0039d316-1c4b-4281-b951-d872f2087c98
int TabStrip::OnDragUpdated(const DropTargetEvent& event) {
  UpdateDropIndex(event);

  if (!drop_info_->file_supported)
    return ui::DragDropTypes::DRAG_NONE;

  return GetDropEffect(event);
}

int TabStrip::OnDragUpdated(const DropTargetEvent& event) {
  UpdateDropIndex(event);

  if (!drop_info_->file_supported)
    return ui::DragDropTypes::DRAG_NONE;

  return GetDropEffect(event);
}
