Chrome Version       : 69.0.3464.0

Tracking bug is Issue 705669

https://medium.com/dailyjs/image-loading-with-image-decode-b03652e7d2d2

https://html.spec.whatwg.org/multipage/embedded-content.html#dom-img-decode

This idea isn't fully-baked, but I noticed the Gallery image loader has some tricks to avoid freezing the UI
 * 2. Copies pixels from HTMLImageElement to HTMLCanvasElement. This is done
 *    stripe-by-stripe to avoid freezing up the UI. The transform is taken into
 *    account.

I think img.decode() API would help even sooner (i.e. before we copy to a Canvas [#canvaswhy])

file_manager/foreground/js/thumbnail_loader.js also seems to be using the HTMLImageElement.onload() approach which the medium.com article specifically calls out as "current practice" which can now be improved upon.