Renamed “touch-icon-196x196.png” to “chrome-touch-icon-196x196.png” (because that’s what it is). Moved the <link> to the appropriate <meta> (and fixed the “rel”). Removed the 57x57 pixel icon.
Optimized the images and added “icon-128x128.png” (see https://developer.mozilla.org/en-US/Apps/Build/Manifest#icons).