Google has removed support for NPAPI in Chrome for Linux, and will remove it from all platforms from September 2015.
The consequence for Webmin is that the File Manager (my favourite bit) does not work in Chrome for Linux, and will not work on any platform after September. I have been reduced to using Firefox for Webmin, but I fear that Firefox (and other browsers) will follow Chrome’s lead eventually - apparently it is a “security” thing.
More information is available here: http://www.chromium.org/developers/npapi-deprecation
Here’s hoping that the File Manager is refactored to use a different technology!