Prevent leaking PDF data cross-origin

BUG=520422

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

Cr-Commit-Position: refs/heads/master@{#345267}
pp::Var OutOfProcessInstance::GetLinkAtPosition(
    const pp::Point& point) {
  pp::Point offset_point(point);
  ScalePoint(device_scale_, &offset_point);
  offset_point.set_x(offset_point.x() - available_area_.x());
  return engine_->GetLinkAtPosition(offset_point);
}

pp::Var OutOfProcessInstance::GetLinkAtPosition(
    const pp::Point& point) {
  pp::Point offset_point(point);
  ScalePoint(device_scale_, &offset_point);
  offset_point.set_x(offset_point.x() - available_area_.x());
  return engine_->GetLinkAtPosition(offset_point);
}
