Prevent leaking PDF data cross-origin

BUG=520422

Review URL: https://codereview.chromium.org/1311973002

Cr-Commit-Position: refs/heads/master@{#345267}
bool OutOfProcessInstance::IsPrintPreview() {
  return IsPrintPreviewUrl(url_);
}

bool OutOfProcessInstance::IsPrintPreview() {
  return IsPrintPreviewUrl(url_);
}
