How-To Geek explains what the heck they actually do.

Native Client: This allows developers to run C or C++ code on a web site.

Adobe Flash: This is Adobe Flash, but tweaked a bit for Google Chrome.

Chrome Remote Desktop Viewer: This is the Chrome Remote Desktop app needed to access your gear remotely.

The plug-in doesn’t do anything unless you activate it.

it’s possible for you to alwaysdisable any of these, but you’ll lose functionality as expected.

Google Chrome Includes 5 surfing app Plug-Ins, and Here’s What They Do| How-To Geek