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

/cc @alespergl 
atom/common/api/atom_api_native_image.cc
const base::FilePath& path,
                     double scale_factor) {
  std::string file_contents;
  if (!asar::ReadFileToString(path, &file_contents))
    return false;
  const unsigned char* data =
      reinterpret_cast<const unsigned char*>(file_contents.data());
  size_t size = file_contents.size();
  return AddImageSkiaRep(image, data, size, 0, 0, scale_factor);
}
bool PopulateImageSkiaRepsFromPath(gfx::ImageSkia* image,
                                   const base::FilePath& path) {
  bool succeed = false;
  std::string filename(path.BaseName().RemoveExtension().AsUTF8Unsafe());
  if (base::MatchPattern(filename, "*@*x"))
    
    return AddImageSkiaRep(image, path, GetScaleFactorFromPath(path));
  else
    succeed |= AddImageSkiaRep(image, path, 1.0f);
  for (const ScaleFactorPair& pair : kScaleFactorPairs)
    succeed |= AddImageSkiaRep(image,
                               path.InsertBeforeExtensionASCII(pair.name),
                               pair.scale);
  return succeed;
}
base::FilePath NormalizePath(const base::FilePath& path) {