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

/cc @alespergl 
atom/common/api/atom_api_native_image.cc
const unsigned char* data,
                     size_t size,
                     int width,
                     int height,
                     double scale_factor) {
  std::unique_ptr<SkBitmap> decoded(new SkBitmap());
  
  if (!gfx::PNGCodec::Decode(data, size, decoded.get()))
    
    decoded = gfx::JPEGCodec::Decode(data, size);
  if (!decoded) {
    
    if (width > 0 && height > 0) {
      decoded.reset(new SkBitmap);
      decoded->allocN32Pixels(width, height, false);
      decoded->setPixels(
        const_cast<void*>(reinterpret_cast<const void*>(data)));
    } else {
      return false;
    }
  }
  image->AddRepresentation(gfx::ImageSkiaRep(*decoded, scale_factor));
  return true;
}
bool AddImageSkiaRep(gfx::ImageSkia* image,