Viewing and creating MHTML files in current versions of Google Chrome is supported by toggling the "Save Page as MHTML" option on the chrome://flags
page.
However, enabling this experimental option disables saving pages as HTML-only or HTML Complete files. From the chrome://flags
page:
Save Page as MHTML Mac, Windows, Linux
Disables saving pages as HTML-only or HTML Complete; enables saving pages only as MHTML: a single text file containing HTML and all sub-resources.