Problem: On my Samsung HDTV set, I found that many apps (particularly Chrome) were getting key parts of their screens cut off by overscan. But I couldn't find a way to set the overscan on my HDTV or in the Nexus Player.
Solution: While I was playing around with Nova Launcher on the Nexus Player, I found a way to launch something called "Overscan Calibrator" which fixed the issue!
Here's how I did it:
(1) Install Sideload Launcher (so you can launch Nova Launcher)
(2) Sideload Nova Launcher
(3) Use Sideload Launcher to launch Nova Launcher
(4) In Nova Launcher, long click on the screen to bring up the "Add to Homescreen" menu
(5) Shortcuts -> Activities
(6) Scroll down to find "Overscan Calibrator"
(7) Click on it to open the selection and click on the revealed item to add it to the home screen
(8) Now launch "Overscan Calibrator" and adjust the screen so that then entire screen is visible
Then... your entire Chrome screen will be visible !