They were disabled during the Chromium 61 upgrade. Fix them and enable.

/cc @alespergl 
atom/common/api/atom_api_native_image.cc
std::string filename(path.BaseName().RemoveExtension().AsUTF8Unsafe());
  
  
  for (const auto& kScaleFactorPair : kScaleFactorPairs) {
    if (base::EndsWith(filename, kScaleFactorPair.name,
                       base::CompareCase::INSENSITIVE_ASCII))
      return kScaleFactorPair.scale;
  }
  return 1.0f;
}
float GetScaleFactorFromOptions(mate::Arguments* args) {
  float scale_factor = 1.0f;
  mate::Dictionary options;
  if (args->GetNext(&options))
    options.Get("scaleFactor", &scale_factor);
  return scale_factor;
}
bool AddImageSkiaRep(gfx::ImageSkia* image,