FYI: "chrome://plugins" will no longer work
An FYI to anyone who, like me, was occasionally enabling/disabling Flash or the internal PDF viewer: The chrome://plugins URL will not work from now on (as of the snapshot 1.8.770.9 upgrade to Chromium 57).
Welcome to the Chrome community. According to our team, the plugins link was removed in Chrome 57 and above since a majority of the information on this page is no longer relevant and outdated. More information about this is on our public bug tracker and see the first comment about rationale and supporting rationale to show the reasons why the team decided to remove this page.
The good news is most of the listed items on the plugins page has just moved into the content settings which you can access by clicking the more menu (three dots) > settings > advance > privacy and security > content settings or simply navigating to chrome://settings/content.
So if you want to disable/reenable Flash or PDF-in-browser, do so there, scrolling down to the sections that say "Flash" and "PDF Documents" (Note: You may need to add a space after that URL, and then hit Enter. I'm currently getting redirected to Vivaldi's Settings interface if I just paste in "chrome://settings/content" and hit enter.) Presumably these options, like others, will eventually be integrated into Vivaldi's own settings interface.
See more info also at http://www.ghacks.net/2017/01/29/google-removes-plugin-controls-from-chrome/
That's a shame, it would be great if Vivaldi could work around this and bring the site/settings back, because there are more plugins than only flash and pdf.
@luetage: Chromium did this, obviously. Developers are looking at a way to bring it back.
Chromium/Chrome (also Firefox) won't load any other 3rd party plugins anymore except Flash. Widevine libraries still there, but also suppose to be can't be disabled/enabled.
It's that reason Chromium/Chrome decide to just remove Flash disable/enable UI, it won't be anything else in plugins page if that page stay.
Removing access ability to Flash & Widevine libraries seem the only easiest way.
I have one way come in mind.
Of course there's also a userscipt that completely hide any browser plugins from detection.