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}
void LocalFrame::Init() {
  CoreInitializer::GetInstance().InitLocalFrame(*this);

  loader_.Init();
}

void LocalFrame::Init() {
  CoreInitializer::GetInstance().InitLocalFrame(*this);

  loader_.Init();
}
