Prevent sandboxed documents from reusing the default window

Bug: 377995
Change-Id: Iff66c6d214dfd0cb7ea9c80f83afeedfff703541
Reviewed-on: https://chromium-review.googlesource.com/983558
Commit-Queue: Andy Paicu <andypaicu@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567663}
PluginData* LocalFrame::GetPluginData() const {
  if (!Loader().AllowPlugins(kNotAboutToInstantiatePlugin))
    return nullptr;
  return GetPage()->GetPluginData(
      Tree().Top().GetSecurityContext()->GetSecurityOrigin());
}

PluginData* LocalFrame::GetPluginData() const {
  if (!Loader().AllowPlugins(kNotAboutToInstantiatePlugin))
    return nullptr;
  return GetPage()->GetPluginData(
      Tree().Top().GetSecurityContext()->GetSecurityOrigin());
}
