Not sure on Chrome but in Firefox there are changes coming that disable Flash and other add on's from automatically running.

I've been seeing pop ups on sites where flash is required that you have to enable flash to run on that site and Most times you can enable to to always run on that site.

Flash is set to be phased out by 2020

https://blog.mozilla.org/futurereleases/2017/07/25/firefox-roadmap-flash-end-life/