static estimateWebPSizeFromDimensions(imageElement) {
    const totalPixels = imageElement.naturalWidth * imageElement.naturalHeight;
    // See uses-optimized-images for the rationale behind our 2 byte-per-pixel baseline and
    // JPEG compression ratio of 8:1.
    // WebP usually gives ~20% additional savings on top of that, so we will use 10:1.
    // This is quite pessimistic as their study shows a photographic compression ratio of ~29:1.
    // https://developers.google.com/speed/webp/docs/webp_lossless_alpha_study#results
    const expectedBytesPerPixel = 2 * 1 / 10;
    return Math.round(totalPixels * expectedBytesPerPixel);
  }
@param {{naturalWidth: number, naturalHeight: number}} imageElement
@return {number}